This ensures that these quoted likely forwards references in
return type annotations behave like their non-quoted equivalents.
I suspect there may be other places which will need similar
adjustments, which may mean that we should push the conversion
a layer closer to the parsing (perhaps in `py__annotations__`?).
One case I know that this doesn't solve (but which likely needs
similar adjustment) is generics in return types of comment-style
annotations. They're less likely and may not be worth supporting
since all supported Python versions can use the in-syntax spelling
for annotations at this point.
This builds on the approach taken in https://github.com/davidhalter/jedi/pull/1613
but applies it to type vars themselves so that their type var
nature is preserved when a function returns Callable[[T], T] and
the T has an upper bound.
While these definitely _ought_ to work on Python 2.7, the annotation
support there is very limited and as Python 2 is deprecated it
doesn't seem worth it.
