[Completion] Add a test case for CaseIterable enum in other file
[Completion] Add a test case for CaseIterable enum in other file

Make sure 'allCases' is suggested even if the enum decl is in a
different file.

rdar://problem/57489427

xwu/swift,jmgc/swift,tkremenek/swift,apple/swift,glessard/swift,airspeedswift/swift,ahoppen/swift,JGiola/swift,JGiola/swift,hooman/swift,jckarter/swift,glessard/swift,parkera/swift,roambotics/swift,roambotics/swift,jckarter/swift,lorentey/swift,benlangmuir/swift,nathawes/swift,lorentey/swift,rudkx/swift,gregomni/swift,gregomni/swift,gregomni/swift,parkera/swift,apple/swift,stephentyrone/swift,gribozavr/swift,rudkx/swift,jmgc/swift,ahoppen/swift,jmgc/swift,karwa/swift,stephentyrone/swift,harlanhaskins/swift,gribozavr/swift,stephentyrone/swift,JGiola/swift,karwa/swift,jckarter/swift,glessard/swift,gribozavr/swift,JGiola/swift,jmgc/swift,gribozavr/swift,gribozavr/swift,allevato/swift,roambotics/swift,xwu/swift,karwa/swift,allevato/swift,rudkx/swift,parkera/swift,tkremenek/swift,atrick/swift,jckarter/swift,jckarter/swift,apple/swift,CodaFi/swift,allevato/swift,apple/swift,jmgc/swift,benlangmuir/swift,gregomni/swift,ahoppen/swift,aschwaighofer/swift,stephentyrone/swift,parkera/swift,harlanhaskins/swift,tkremenek/swift,hooman/swift,JGiola/swift,CodaFi/swift,jckarter/swift,rudkx/swift,roambotics/swift,xwu/swift,allevato/swift,parkera/swift,nathawes/swift,glessard/swift,CodaFi/swift,gribozavr/swift,benlangmuir/swift,benlangmuir/swift,rudkx/swift,nathawes/swift,xwu/swift,aschwaighofer/swift,CodaFi/swift,benlangmuir/swift,gribozavr/swift,hooman/swift,jckarter/swift,airspeedswift/swift,aschwaighofer/swift,roambotics/swift,airspeedswift/swift,CodaFi/swift,lorentey/swift,atrick/swift,glessard/swift,roambotics/swift,nathawes/swift,stephentyrone/swift,harlanhaskins/swift,atrick/swift,airspeedswift/swift,parkera/swift,lorentey/swift,aschwaighofer/swift,CodaFi/swift,hooman/swift,JGiola/swift,nathawes/swift,karwa/swift,aschwaighofer/swift,xwu/swift,parkera/swift,tkremenek/swift,gregomni/swift,aschwaighofer/swift,allevato/swift,airspeedswift/swift,stephentyrone/swift,harlanhaskins/swift,gregomni/swift,allevato/swift,gribozavr/swift,ahoppen/swift,airspeedswift/swift,harlanhaskins/swift,lorentey/swift,atrick/swift,jmgc/swift,hooman/swift,ahoppen/swift,atrick/swift,karwa/swift,karwa/swift,nathawes/swift,tkremenek/swift,airspeedswift/swift,karwa/swift,CodaFi/swift,tkremenek/swift,nathawes/swift,benlangmuir/swift,lorentey/swift,ahoppen/swift,jmgc/swift,allevato/swift,karwa/swift,aschwaighofer/swift,xwu/swift,hooman/swift,rudkx/swift,lorentey/swift,stephentyrone/swift,apple/swift,xwu/swift,parkera/swift,atrick/swift,apple/swift,harlanhaskins/swift,glessard/swift,lorentey/swift,tkremenek/swift,hooman/swift,harlanhaskins/swift