Showing the type annotation only makes sense if they are not `Void`. That’s consistent with functions where we also don’t show a `Void` return type. Most importantly, we shouldn’t be showing a `Void` type annotation for attached macros.
rdar://108870970
We need to teach code completion how to invoke the type checker for attached macro attributes. After that, everything started working.
rdar://105232015
Only return macros that are valid in their current position, ie. an
attached macro is not valid on a nominal.
Also return freestanding expression macros in code block item position
and handle the new freestanding code item macros.
Resolves rdar://105563583.
