[sema] Add compiler fixit for the case where a raw-representable type is constructed from an argument with the same type. (#2863)
Like this:
  MyEnumType(MyEnumType.foo)
This is missing 'rawValue:' label, but that won't actually fix this. A better fix is to just remove the unnecessary constructor call:
  MyEnumType(MyEnumType.foo)
-->
  MyEnumType.foo