Move RuleKey to a separate package.
Move RuleKey to a separate package.

Summary:
This makes it simpler to land some subsequent changes which
would otherwise have introduced a cycle.

Test Plan: CI

clonetwin26/buck,justinmuller/buck,bocon13/buck,janicduplessis/buck,sdwilsh/buck,vschs007/buck,brettwooldridge/buck,JoelMarcey/buck,vine/buck,vschs007/buck,justinmuller/buck,dushmis/buck,illicitonion/buck,LegNeato/buck,k21/buck,shybovycha/buck,mogers/buck,tgummerer/buck,sdwilsh/buck,rhencke/buck,JoelMarcey/buck,rmaz/buck,k21/buck,artiya4u/buck,clonetwin26/buck,k21/buck,pwz3n0/buck,Distrotech/buck,liuyang-li/buck,rhencke/buck,lukw00/buck,rmaz/buck,dushmis/buck,nguyentruongtho/buck,rmaz/buck,zpao/buck,justinmuller/buck,mogers/buck,grumpyjames/buck,dushmis/buck,mikekap/buck,rhencke/buck,sdwilsh/buck,rowillia/buck,daedric/buck,OkBuilds/buck,ilya-klyuchnikov/buck,rmaz/buck,nguyentruongtho/buck,robbertvanginkel/buck,bocon13/buck,stuhood/buck,JoelMarcey/buck,davido/buck,brettwooldridge/buck,raviagarwal7/buck,zhan-xiong/buck,janicduplessis/buck,clonetwin26/buck,shs96c/buck,JoelMarcey/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,Learn-Android-app/buck,clonetwin26/buck,brettwooldridge/buck,rowillia/buck,raviagarwal7/buck,Dominator008/buck,pwz3n0/buck,justinmuller/buck,sdwilsh/buck,LegNeato/buck,JoelMarcey/buck,robbertvanginkel/buck,kageiit/buck,SeleniumHQ/buck,pwz3n0/buck,grumpyjames/buck,mogers/buck,shs96c/buck,romanoid/buck,LegNeato/buck,sdwilsh/buck,mikekap/buck,stuhood/buck,k21/buck,mikekap/buck,LegNeato/buck,justinmuller/buck,brettwooldridge/buck,clonetwin26/buck,grumpyjames/buck,zpao/buck,janicduplessis/buck,shs96c/buck,mogers/buck,Addepar/buck,daedric/buck,OkBuilds/buck,JoelMarcey/buck,shybovycha/buck,tgummerer/buck,rowillia/buck,sdwilsh/buck,shs96c/buck,brettwooldridge/buck,LegNeato/buck,darkforestzero/buck,lukw00/buck,janicduplessis/buck,vine/buck,mikekap/buck,rhencke/buck,tgummerer/buck,davido/buck,shybovycha/buck,OkBuilds/buck,Learn-Android-app/buck,justinmuller/buck,romanoid/buck,davido/buck,Dominator008/buck,LegNeato/buck,ilya-klyuchnikov/buck,Dominator008/buck,janicduplessis/buck,illicitonion/buck,vschs007/buck,daedric/buck,dsyang/buck,shs96c/buck,rmaz/buck,mogers/buck,artiya4u/buck,Dominator008/buck,vschs007/buck,darkforestzero/buck,liuyang-li/buck,illicitonion/buck,Dominator008/buck,shybovycha/buck,OkBuilds/buck,grumpyjames/buck,dsyang/buck,shybovycha/buck,Learn-Android-app/buck,liuyang-li/buck,k21/buck,Addepar/buck,marcinkwiatkowski/buck,facebook/buck,dushmis/buck,robbertvanginkel/buck,Dominator008/buck,dushmis/buck,daedric/buck,tgummerer/buck,janicduplessis/buck,clonetwin26/buck,grumpyjames/buck,LegNeato/buck,ilya-klyuchnikov/buck,Learn-Android-app/buck,facebook/buck,bocon13/buck,k21/buck,davido/buck,zpao/buck,artiya4u/buck,Dominator008/buck,bocon13/buck,vine/buck,rhencke/buck,rhencke/buck,zpao/buck,dushmis/buck,darkforestzero/buck,clonetwin26/buck,rhencke/buck,ilya-klyuchnikov/buck,vine/buck,vine/buck,grumpyjames/buck,Distrotech/buck,raviagarwal7/buck,mikekap/buck,janicduplessis/buck,LegNeato/buck,illicitonion/buck,rowillia/buck,liuyang-li/buck,rhencke/buck,janicduplessis/buck,zhan-xiong/buck,darkforestzero/buck,lukw00/buck,bocon13/buck,marcinkwiatkowski/buck,janicduplessis/buck,clonetwin26/buck,ilya-klyuchnikov/buck,mogers/buck,justinmuller/buck,mogers/buck,facebook/buck,SeleniumHQ/buck,zhan-xiong/buck,romanoid/buck,liuyang-li/buck,tgummerer/buck,shs96c/buck,daedric/buck,Dominator008/buck,ilya-klyuchnikov/buck,tgummerer/buck,mikekap/buck,brettwooldridge/buck,shs96c/buck,romanoid/buck,zhan-xiong/buck,darkforestzero/buck,dsyang/buck,shybovycha/buck,shybovycha/buck,rowillia/buck,raviagarwal7/buck,shybovycha/buck,Learn-Android-app/buck,mogers/buck,tgummerer/buck,k21/buck,stuhood/buck,mikekap/buck,ilya-klyuchnikov/buck,Distrotech/buck,grumpyjames/buck,LegNeato/buck,mogers/buck,liuyang-li/buck,Dominator008/buck,OkBuilds/buck,Addepar/buck,JoelMarcey/buck,lukw00/buck,rmaz/buck,janicduplessis/buck,Distrotech/buck,lukw00/buck,stuhood/buck,tgummerer/buck,dsyang/buck,davido/buck,sdwilsh/buck,nguyentruongtho/buck,robbertvanginkel/buck,davido/buck,raviagarwal7/buck,romanoid/buck,Distrotech/buck,dsyang/buck,mikekap/buck,vine/buck,zpao/buck,vschs007/buck,mikekap/buck,brettwooldridge/buck,justinmuller/buck,OkBuilds/buck,zhan-xiong/buck,nguyentruongtho/buck,bocon13/buck,daedric/buck,liuyang-li/buck,marcinkwiatkowski/buck,facebook/buck,artiya4u/buck,darkforestzero/buck,sdwilsh/buck,grumpyjames/buck,OkBuilds/buck,liuyang-li/buck,sdwilsh/buck,liuyang-li/buck,SeleniumHQ/buck,SeleniumHQ/buck,dsyang/buck,vine/buck,artiya4u/buck,marcinkwiatkowski/buck,clonetwin26/buck,rmaz/buck,brettwooldridge/buck,brettwooldridge/buck,raviagarwal7/buck,grumpyjames/buck,illicitonion/buck,k21/buck,OkBuilds/buck,robbertvanginkel/buck,rowillia/buck,nguyentruongtho/buck,rhencke/buck,rowillia/buck,daedric/buck,zhan-xiong/buck,davido/buck,rowillia/buck,shybovycha/buck,justinmuller/buck,pwz3n0/buck,rhencke/buck,Distrotech/buck,shs96c/buck,JoelMarcey/buck,shs96c/buck,raviagarwal7/buck,vschs007/buck,kageiit/buck,raviagarwal7/buck,pwz3n0/buck,stuhood/buck,marcinkwiatkowski/buck,brettwooldridge/buck,davido/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,janicduplessis/buck,Dominator008/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,Addepar/buck,JoelMarcey/buck,bocon13/buck,shybovycha/buck,tgummerer/buck,darkforestzero/buck,romanoid/buck,Learn-Android-app/buck,liuyang-li/buck,facebook/buck,nguyentruongtho/buck,pwz3n0/buck,daedric/buck,artiya4u/buck,pwz3n0/buck,zpao/buck,illicitonion/buck,SeleniumHQ/buck,robbertvanginkel/buck,stuhood/buck,lukw00/buck,Learn-Android-app/buck,artiya4u/buck,Addepar/buck,romanoid/buck,Addepar/buck,marcinkwiatkowski/buck,pwz3n0/buck,bocon13/buck,JoelMarcey/buck,lukw00/buck,Addepar/buck,marcinkwiatkowski/buck,artiya4u/buck,stuhood/buck,mogers/buck,davido/buck,brettwooldridge/buck,shs96c/buck,LegNeato/buck,darkforestzero/buck,grumpyjames/buck,raviagarwal7/buck,vschs007/buck,zhan-xiong/buck,illicitonion/buck,robbertvanginkel/buck,k21/buck,darkforestzero/buck,Learn-Android-app/buck,rmaz/buck,shs96c/buck,dushmis/buck,darkforestzero/buck,artiya4u/buck,kageiit/buck,Learn-Android-app/buck,facebook/buck,zhan-xiong/buck,ilya-klyuchnikov/buck,marcinkwiatkowski/buck,rhencke/buck,lukw00/buck,SeleniumHQ/buck,mikekap/buck,k21/buck,SeleniumHQ/buck,illicitonion/buck,vine/buck,illicitonion/buck,robbertvanginkel/buck,dushmis/buck,sdwilsh/buck,daedric/buck,daedric/buck,dsyang/buck,rowillia/buck,LegNeato/buck,romanoid/buck,ilya-klyuchnikov/buck,pwz3n0/buck,grumpyjames/buck,Addepar/buck,SeleniumHQ/buck,OkBuilds/buck,vine/buck,rmaz/buck,k21/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,davido/buck,daedric/buck,Distrotech/buck,Addepar/buck,OkBuilds/buck,Distrotech/buck,dushmis/buck,Distrotech/buck,Distrotech/buck,clonetwin26/buck,davido/buck,bocon13/buck,Distrotech/buck,shybovycha/buck,robbertvanginkel/buck,Addepar/buck,clonetwin26/buck,artiya4u/buck,Learn-Android-app/buck,sdwilsh/buck,stuhood/buck,rmaz/buck,dsyang/buck,sdwilsh/buck,OkBuilds/buck,Addepar/buck,mogers/buck,rowillia/buck,zhan-xiong/buck,pwz3n0/buck,rmaz/buck,shybovycha/buck,justinmuller/buck,justinmuller/buck,LegNeato/buck,dsyang/buck,kageiit/buck,Dominator008/buck,rowillia/buck,ilya-klyuchnikov/buck,stuhood/buck,pwz3n0/buck,Addepar/buck,SeleniumHQ/buck,shs96c/buck,illicitonion/buck,romanoid/buck,bocon13/buck,facebook/buck,tgummerer/buck,stuhood/buck,brettwooldridge/buck,raviagarwal7/buck,vschs007/buck,dsyang/buck,JoelMarcey/buck,ilya-klyuchnikov/buck,romanoid/buck,vine/buck,rmaz/buck,zhan-xiong/buck,zhan-xiong/buck,rmaz/buck,vschs007/buck,lukw00/buck,zhan-xiong/buck,JoelMarcey/buck,vschs007/buck,OkBuilds/buck,rowillia/buck,raviagarwal7/buck,daedric/buck,davido/buck,k21/buck,SeleniumHQ/buck,Dominator008/buck,kageiit/buck,davido/buck,darkforestzero/buck,romanoid/buck,vschs007/buck,zhan-xiong/buck,robbertvanginkel/buck,dushmis/buck,lukw00/buck,kageiit/buck,robbertvanginkel/buck,romanoid/buck,mikekap/buck,romanoid/buck,zpao/buck,justinmuller/buck,k21/buck,marcinkwiatkowski/buck,stuhood/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,vschs007/buck,kageiit/buck,nguyentruongtho/buck,vine/buck,shybovycha/buck,liuyang-li/buck,sdwilsh/buck,grumpyjames/buck,illicitonion/buck,OkBuilds/buck,illicitonion/buck,raviagarwal7/buck,clonetwin26/buck,vschs007/buck,darkforestzero/buck,janicduplessis/buck,SeleniumHQ/buck,daedric/buck,bocon13/buck,shs96c/buck,raviagarwal7/buck,mikekap/buck,Learn-Android-app/buck,dsyang/buck,darkforestzero/buck,lukw00/buck,dsyang/buck,dsyang/buck,LegNeato/buck,illicitonion/buck,JoelMarcey/buck,clonetwin26/buck,justinmuller/buck,artiya4u/buck,robbertvanginkel/buck,Addepar/buck,bocon13/buck,tgummerer/buck