[CSClosure] Generalize syntactic element simplification
[CSClosure] Generalize syntactic element simplification

Syntactic elements could be found in a closure or an accessor
which could also be a result builder.

benlangmuir/swift,glessard/swift,glessard/swift,apple/swift,JGiola/swift,glessard/swift,JGiola/swift,benlangmuir/swift,roambotics/swift,apple/swift,benlangmuir/swift,benlangmuir/swift,JGiola/swift,JGiola/swift,apple/swift,roambotics/swift,benlangmuir/swift,apple/swift,glessard/swift,JGiola/swift,benlangmuir/swift,roambotics/swift,apple/swift,roambotics/swift,apple/swift,JGiola/swift,roambotics/swift,roambotics/swift,glessard/swift,glessard/swift