Add locations for names bound in except handlers

[hauntsaninja]

See this PR python/mypy#21153
Once this has been fixed, we can unskip the test
Similar thing might apply elsewhere, e.g. with statements

[ilevkivskyi]

Btw this will require some care w.r.t. backwards compatibility, otherwise if we release a new version of ast_serialize with this, it will break old mypy 1.20.

@JukkaL I think we should do something like this: modify the signature of parse() to include an optional argument like cache_version: int = 0. And newer versions of mypy will then ask for newer cache_version. Essentially, this would play a role similar to API version in librt.