…h stringified annotations (pythonGH-138953)

This issue appears specifically for TypedDicts because the TypedDict constructor
code converts string annotations to ForwardRef objects, and those are not evaluated
properly by the get_type_hints() stack because of other shenanigans with type
parameters.

This issue does not affect normal generic classes because their annotations are not
pre-converted to ForwardRefs.

The fix attempts to restore the pre- pythonGH-137227 behavior in the narrow scenario where
the issue manifests. It mostly makes changes only in the paths accessible from get_type_hints(),
ensuring that newer APIs (such as evaluate_forward_ref() and annotationlib) are not affected
by get_type_hints()'s past odd choices. This PR does not fix issue pythonGH-138949, an older issue I
discovered while playing around with this one; we'll need a separate and perhaps more
invasive fix for that, but it should wait until after 3.14.0.
(cherry picked from commit 6d6aba2)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>