Summary

This PR separates out the entirely new tests from #16923 into a standalone PR. I'll rebase #16923 on top of this branch.

The reasons for separating it out are:

• It should make it clearer to see in [red-knot] Add initial support for * imports #16923 exactly how the functionality is changing (we can see the assertions in the tests change, which isn't so obvious if the tests are entirely new)
• The diff on [red-knot] Add initial support for * imports #16923 is getting pretty big; this should reduce the diff on that PR somewhat
• These tests seem useful in and of themselves, so even if we need to do a wholesale revert of [red-knot] Add initial support for * imports #16923 for whatever reason, it'll be nice to keep the tests

Test Plan

cargo test -p red_knot_python_semantic