[ast-dumper] If an existential metatype type has a metatype representation, print it when dumping.
[ast-dumper] If an existential metatype type has a metatype representation, print it when dumping.

This makes it easy when debugging to tell the difference in between metatypes
with differing representations.

rdar://28536812

hooman/swift,swiftix/swift,xwu/swift,apple/swift,tkremenek/swift,ben-ng/swift,amraboelela/swift,gmilos/swift,shajrawi/swift,OscarSwanros/swift,frootloops/swift,sschiau/swift,jopamer/swift,tkremenek/swift,tjw/swift,modocache/swift,tardieu/swift,CodaFi/swift,aschwaighofer/swift,felix91gr/swift,return/swift,JGiola/swift,return/swift,shajrawi/swift,tjw/swift,airspeedswift/swift,shajrawi/swift,tinysun212/swift-windows,atrick/swift,jtbandes/swift,gribozavr/swift,JGiola/swift,allevato/swift,OscarSwanros/swift,djwbrown/swift,brentdax/swift,sschiau/swift,benlangmuir/swift,shahmishal/swift,gmilos/swift,arvedviehweger/swift,stephentyrone/swift,gmilos/swift,gribozavr/swift,harlanhaskins/swift,zisko/swift,huonw/swift,arvedviehweger/swift,harlanhaskins/swift,tjw/swift,gmilos/swift,kstaring/swift,calebd/swift,huonw/swift,glessard/swift,ben-ng/swift,danielmartin/swift,jmgc/swift,uasys/swift,tkremenek/swift,therealbnut/swift,amraboelela/swift,natecook1000/swift,calebd/swift,jtbandes/swift,gottesmm/swift,zisko/swift,zisko/swift,jckarter/swift,CodaFi/swift,devincoughlin/swift,hughbe/swift,apple/swift,hooman/swift,sschiau/swift,hooman/swift,karwa/swift,practicalswift/swift,deyton/swift,milseman/swift,airspeedswift/swift,rudkx/swift,jckarter/swift,gregomni/swift,kstaring/swift,rudkx/swift,bitjammer/swift,calebd/swift,stephentyrone/swift,uasys/swift,arvedviehweger/swift,kstaring/swift,ben-ng/swift,kperryua/swift,shajrawi/swift,alblue/swift,manavgabhawala/swift,frootloops/swift,atrick/swift,JaSpa/swift,gottesmm/swift,sschiau/swift,brentdax/swift,rudkx/swift,gribozavr/swift,swiftix/swift,swiftix/swift,aschwaighofer/swift,airspeedswift/swift,codestergit/swift,huonw/swift,practicalswift/swift,CodaFi/swift,practicalswift/swift,gribozavr/swift,shajrawi/swift,uasys/swift,tinysun212/swift-windows,brentdax/swift,gottesmm/swift,jckarter/swift,jmgc/swift,Jnosh/swift,roambotics/swift,karwa/swift,lorentey/swift,roambotics/swift,airspeedswift/swift,hughbe/swift,lorentey/swift,modocache/swift,karwa/swift,xwu/swift,uasys/swift,kperryua/swift,milseman/swift,therealbnut/swift,danielmartin/swift,tardieu/swift,alblue/swift,parkera/swift,ben-ng/swift,nathawes/swift,gregomni/swift,uasys/swift,gribozavr/swift,harlanhaskins/swift,djwbrown/swift,zisko/swift,kperryua/swift,djwbrown/swift,aschwaighofer/swift,alblue/swift,shahmishal/swift,karwa/swift,therealbnut/swift,ben-ng/swift,tjw/swift,xedin/swift,hughbe/swift,gribozavr/swift,tinysun212/swift-windows,roambotics/swift,devincoughlin/swift,OscarSwanros/swift,shahmishal/swift,parkera/swift,ahoppen/swift,return/swift,milseman/swift,frootloops/swift,harlanhaskins/swift,brentdax/swift,roambotics/swift,hooman/swift,karwa/swift,gregomni/swift,stephentyrone/swift,gottesmm/swift,hughbe/swift,return/swift,jtbandes/swift,uasys/swift,danielmartin/swift,djwbrown/swift,sschiau/swift,shajrawi/swift,sschiau/swift,felix91gr/swift,shahmishal/swift,swiftix/swift,karwa/swift,tjw/swift,zisko/swift,manavgabhawala/swift,stephentyrone/swift,tardieu/swift,bitjammer/swift,nathawes/swift,ben-ng/swift,modocache/swift,atrick/swift,airspeedswift/swift,djwbrown/swift,return/swift,amraboelela/swift,danielmartin/swift,practicalswift/swift,codestergit/swift,frootloops/swift,huonw/swift,djwbrown/swift,jtbandes/swift,shajrawi/swift,nathawes/swift,deyton/swift,bitjammer/swift,jckarter/swift,glessard/swift,return/swift,atrick/swift,tkremenek/swift,aschwaighofer/swift,benlangmuir/swift,jtbandes/swift,calebd/swift,lorentey/swift,allevato/swift,austinzheng/swift,allevato/swift,calebd/swift,parkera/swift,practicalswift/swift,kstaring/swift,manavgabhawala/swift,natecook1000/swift,xwu/swift,JGiola/swift,jopamer/swift,bitjammer/swift,milseman/swift,benlangmuir/swift,danielmartin/swift,Jnosh/swift,kstaring/swift,arvedviehweger/swift,glessard/swift,xwu/swift,lorentey/swift,zisko/swift,jmgc/swift,parkera/swift,devincoughlin/swift,gottesmm/swift,lorentey/swift,kperryua/swift,kstaring/swift,gregomni/swift,swiftix/swift,gregomni/swift,djwbrown/swift,rudkx/swift,JaSpa/swift,atrick/swift,tkremenek/swift,OscarSwanros/swift,OscarSwanros/swift,karwa/swift,roambotics/swift,jopamer/swift,milseman/swift,xedin/swift,jmgc/swift,bitjammer/swift,modocache/swift,felix91gr/swift,airspeedswift/swift,shajrawi/swift,devincoughlin/swift,calebd/swift,felix91gr/swift,jopamer/swift,danielmartin/swift,allevato/swift,atrick/swift,deyton/swift,hooman/swift,tardieu/swift,gribozavr/swift,gottesmm/swift,practicalswift/swift,natecook1000/swift,austinzheng/swift,parkera/swift,glessard/swift,harlanhaskins/swift,gregomni/swift,amraboelela/swift,Jnosh/swift,amraboelela/swift,hooman/swift,kperryua/swift,Jnosh/swift,glessard/swift,jmgc/swift,manavgabhawala/swift,natecook1000/swift,benlangmuir/swift,austinzheng/swift,therealbnut/swift,bitjammer/swift,deyton/swift,JaSpa/swift,kperryua/swift,tinysun212/swift-windows,xedin/swift,shahmishal/swift,jtbandes/swift,kstaring/swift,lorentey/swift,shahmishal/swift,jopamer/swift,tardieu/swift,kperryua/swift,aschwaighofer/swift,shahmishal/swift,alblue/swift,manavgabhawala/swift,amraboelela/swift,ahoppen/swift,codestergit/swift,jmgc/swift,jckarter/swift,devincoughlin/swift,JGiola/swift,huonw/swift,jopamer/swift,practicalswift/swift,tjw/swift,manavgabhawala/swift,milseman/swift,JaSpa/swift,ahoppen/swift,uasys/swift,jmgc/swift,amraboelela/swift,codestergit/swift,xedin/swift,apple/swift,xwu/swift,CodaFi/swift,brentdax/swift,modocache/swift,zisko/swift,brentdax/swift,gribozavr/swift,swiftix/swift,benlangmuir/swift,ahoppen/swift,apple/swift,allevato/swift,tinysun212/swift-windows,tardieu/swift,apple/swift,practicalswift/swift,benlangmuir/swift,xedin/swift,xwu/swift,calebd/swift,huonw/swift,bitjammer/swift,austinzheng/swift,allevato/swift,lorentey/swift,codestergit/swift,JGiola/swift,deyton/swift,danielmartin/swift,felix91gr/swift,aschwaighofer/swift,milseman/swift,xedin/swift,CodaFi/swift,tjw/swift,return/swift,natecook1000/swift,swiftix/swift,JGiola/swift,allevato/swift,harlanhaskins/swift,modocache/swift,roambotics/swift,apple/swift,austinzheng/swift,parkera/swift,deyton/swift,therealbnut/swift,gmilos/swift,tardieu/swift,deyton/swift,hooman/swift,felix91gr/swift,ben-ng/swift,austinzheng/swift,natecook1000/swift,frootloops/swift,gottesmm/swift,natecook1000/swift,JaSpa/swift,hughbe/swift,nathawes/swift,felix91gr/swift,xwu/swift,modocache/swift,arvedviehweger/swift,manavgabhawala/swift,glessard/swift,stephentyrone/swift,tkremenek/swift,frootloops/swift,stephentyrone/swift,codestergit/swift,aschwaighofer/swift,gmilos/swift,arvedviehweger/swift,rudkx/swift,hughbe/swift,tkremenek/swift,devincoughlin/swift,lorentey/swift,ahoppen/swift,xedin/swift,nathawes/swift,ahoppen/swift,brentdax/swift,airspeedswift/swift,OscarSwanros/swift,sschiau/swift,nathawes/swift,parkera/swift,tinysun212/swift-windows,arvedviehweger/swift,shahmishal/swift,CodaFi/swift,austinzheng/swift,jckarter/swift,karwa/swift,jtbandes/swift,parkera/swift,sschiau/swift,devincoughlin/swift,alblue/swift,xedin/swift,Jnosh/swift,codestergit/swift,rudkx/swift,JaSpa/swift,harlanhaskins/swift,tinysun212/swift-windows,Jnosh/swift,jopamer/swift,nathawes/swift,devincoughlin/swift,huonw/swift,OscarSwanros/swift,hughbe/swift,therealbnut/swift,alblue/swift,stephentyrone/swift,alblue/swift,therealbnut/swift,CodaFi/swift,JaSpa/swift,frootloops/swift,jckarter/swift,gmilos/swift,Jnosh/swift