[sil] Make SILType::getCategoryType() use getRawASTType() instead of getASTType().
[sil] Make SILType::getCategoryType() use getRawASTType() instead of getASTType().

The reason why this makes sense is that this method is attempting to return the
current SILType but with a different category. So using getASTType() here and by
mistake removing move only would break semantics. Additionally, not making this
change breaks the expectation that this API would be idempotent.

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