[gardening] Remove uses of "importDeclCached" and cleanup "VisitEnumConstantDecl".
[gardening] Remove uses of "importDeclCached" and cleanup "VisitEnumConstantDecl".

Cleans up the EnumConstantDecl visitor by consolidating cases and
removing calls to "importDeclCached".

xwu/swift,roambotics/swift,jmgc/swift,hooman/swift,benlangmuir/swift,atrick/swift,gregomni/swift,tkremenek/swift,benlangmuir/swift,tkremenek/swift,JGiola/swift,hooman/swift,roambotics/swift,gregomni/swift,benlangmuir/swift,apple/swift,JGiola/swift,roambotics/swift,atrick/swift,jmgc/swift,rudkx/swift,atrick/swift,xwu/swift,glessard/swift,hooman/swift,atrick/swift,ahoppen/swift,parkera/swift,ahoppen/swift,gregomni/swift,apple/swift,xwu/swift,ahoppen/swift,roambotics/swift,tkremenek/swift,roambotics/swift,parkera/swift,tkremenek/swift,benlangmuir/swift,jmgc/swift,gregomni/swift,parkera/swift,tkremenek/swift,JGiola/swift,glessard/swift,hooman/swift,apple/swift,parkera/swift,jmgc/swift,parkera/swift,jmgc/swift,hooman/swift,benlangmuir/swift,ahoppen/swift,apple/swift,JGiola/swift,apple/swift,xwu/swift,xwu/swift,JGiola/swift,xwu/swift,rudkx/swift,apple/swift,benlangmuir/swift,ahoppen/swift,glessard/swift,jmgc/swift,hooman/swift,parkera/swift,tkremenek/swift,gregomni/swift,glessard/swift,roambotics/swift,rudkx/swift,xwu/swift,ahoppen/swift,parkera/swift,atrick/swift,jmgc/swift,rudkx/swift,parkera/swift,hooman/swift,atrick/swift,rudkx/swift,rudkx/swift,JGiola/swift,glessard/swift,tkremenek/swift,gregomni/swift,glessard/swift