build: add missing @babel/generator bazel dep to fix  //packages/localize/src/tools/test:test (#34974)
build: add missing @babel/generator bazel dep to fix  //packages/localize/src/tools/test:test (#34974)

It's not clear how this ever worked (npm hoisting is a suspect though), but this dep is required because
one of the tests imports @babel/generator in the ts sources.

The lack of this dep is breaking builds on the master branch.

More discussion about this issue on Slack: https://angular-team.slack.com/archives/C07DT5M6V/p1579934766007500

PR Close #34974

wKoza/angular,shairez/angular,angular-indonesia/angular,JiaLiPassion/angular,ocombe/angular,JiaLiPassion/angular,StephenFluin/angular,angular/angular,gkalpak/angular,snaptech/angular,ocombe/angular,filipesilva/angular,IdeaBlade/angular,gnomeontherun/angular,alxhub/angular,mgechev/angular,filipesilva/angular,IdeaBlade/angular,angular-indonesia/angular,manekinekko/angular,angular-indonesia/angular,angular-indonesia/angular,filipesilva/angular,snaptech/angular,StephenFluin/angular,wKoza/angular,angular/angular,angular/angular,JiaLiPassion/angular,ocombe/angular,ocombe/angular,alxhub/angular,manekinekko/angular,Toxicable/angular,gdi2290/angular,manekinekko/angular,matsko/angular,brandonroberts/angular,brandonroberts/angular,shairez/angular,matsko/angular,IdeaBlade/angular,blesh/angular,JiaLiPassion/angular,snaptech/angular,brandonroberts/angular,gnomeontherun/angular,Toxicable/angular,StephenFluin/angular,gdi2290/angular,gkalpak/angular,blesh/angular,manekinekko/angular,mgechev/angular,brandonroberts/angular,snaptech/angular,mgechev/angular,StephenFluin/angular,wKoza/angular,wKoza/angular,filipesilva/angular,blesh/angular,gdi2290/angular,shairez/angular,manekinekko/angular,snaptech/angular,matsko/angular,gnomeontherun/angular,manekinekko/angular,shairez/angular,Toxicable/angular,gnomeontherun/angular,StephenFluin/angular,gkalpak/angular,Toxicable/angular,mgechev/angular,ocombe/angular,gdi2290/angular,brandonroberts/angular,gdi2290/angular,ocombe/angular,gkalpak/angular,gdi2290/angular,IdeaBlade/angular,alxhub/angular,matsko/angular,mgechev/angular,filipesilva/angular,angular/angular,alxhub/angular,wKoza/angular,blesh/angular,shairez/angular,Toxicable/angular,IdeaBlade/angular,matsko/angular,alxhub/angular,snaptech/angular,Toxicable/angular,brandonroberts/angular,blesh/angular,wKoza/angular