Make tests pass on conda builds

[AlexWaygood]

The test suite doesn't currently pass on conda builds of Python. This is somewhat annoying for me personally, as I generally use conda when I want to use an older version of Python, and testing on older versions of Python is pretty important for typing_extensions :)

The main reason why the tests fail on conda is that conda debundles the test package from the standard library. This PR just vendors test.ann_module, test.ann_module2 and test.ann_module3 from the CPython main branch (and renames them as _ann_module, _ann_module2, and _ann_module3). This is probably a good thing to do anyway; the Lib/test directory is sort of an implementation detail of CPython's internal test suite.

There was also an Any test that was failing on Python <3.11 due to the module of a nested class being __main__ instead of typing_extensions. I'm not sure why this is different on conda, but it doesn't seem that big a deal to just change the test here.

[hauntsaninja]

Hmm, will these get distributed to users? Maybe it would be cleaner to inline into test_typing_extensions and exec?

[AlexWaygood]

Maybe it would be cleaner to inline into test_typing_extensions and exec?

Could do! We already have src/_typed_dict_test_helper.py on the main branch, though I guess that also isn't ideal now that you mention it.

What about creating an src/test_data directory for putting these files in? That would have the (small, but nice) advantage that we'd still get syntax highlighting on GitHub/IDEs.

[JelleZijlstra]

We definitely should make it so these files don't get put into people's site-packages on installation. I think I prefer inlining the files into test_typing_extensions so we don't have to deal with the complexity of distributing the additional files.

[AlexWaygood]

There may be a simpler way of doing this, but I couldn't immediately figure it out