require an ownership specifier for noncopyable parameters
Per the current proposal, these are to be specified
explicitly, as they form an important part of the API.
Bonus: This commit includes a fix to make
`CompileTimeConstTypeRepr` a proper `isa<>` subtype of
`SpecifierTypeRepr`, since we forgot to add it to
that type's `classof` function.
resolves rdar://105480354
