[PreCheck] Allow pre-check to walk into patterns when multi-statement inference is disabled
[PreCheck] Allow pre-check to walk into patterns when multi-statement inference is disabled

This restores original pre-check behavior and is important for diagnostics
like `'_' can only appear in a pattern or on the left side of an assignment`.

ahoppen/swift,benlangmuir/swift,benlangmuir/swift,rudkx/swift,ahoppen/swift,rudkx/swift,atrick/swift,apple/swift,xwu/swift,xwu/swift,roambotics/swift,roambotics/swift,ahoppen/swift,JGiola/swift,gregomni/swift,ahoppen/swift,ahoppen/swift,xwu/swift,glessard/swift,xwu/swift,JGiola/swift,JGiola/swift,roambotics/swift,gregomni/swift,glessard/swift,JGiola/swift,benlangmuir/swift,atrick/swift,xwu/swift,benlangmuir/swift,roambotics/swift,apple/swift,roambotics/swift,ahoppen/swift,atrick/swift,glessard/swift,benlangmuir/swift,glessard/swift,apple/swift,gregomni/swift,apple/swift,JGiola/swift,xwu/swift,rudkx/swift,JGiola/swift,rudkx/swift,gregomni/swift,apple/swift,glessard/swift,glessard/swift,gregomni/swift,benlangmuir/swift,xwu/swift,atrick/swift,rudkx/swift,apple/swift,atrick/swift,rudkx/swift,gregomni/swift,roambotics/swift,atrick/swift