[3.13] gh-125608: Trigger dictionary watchers when inline values change (GH-125611) (GH-125982)

Dictionary watchers on an object's attributes dictionary
(`object.__dict__`) were not triggered when the managed dictionary used
the object's inline values.
(cherry picked from commit 5989eb74463c26780632f17f221d6bf4c9372a01)

Co-authored-by: Sam Gross <colesbury@gmail.com>