gh-130425: Add "Did you mean [...]" suggestions for del obj.attr

[Pranjal095]

Merges PR #130427 implementing delattr suggestions by @sobolevn and PR #130455 adding tests for the feature by @Pranjal095

Note: This PR's sole purpose is to combine the feature implementation from PR #130427 with the test cases from PR #130455. All original commits have been preserved to retain proper authorship.

• Issue: Provide name suggestions for failed attribute deletions #130425

[sobolevn]

I also don't think that merging a fix with tests into one PR is a good idea. When we have a fix and new tests - we usually merge them as different PRs, that's the first time I see that we combine PRs :)

[sobolevn]

Sorry, I don't quite like the current design :(
It would be even more complex, when we add setattr tests (btw, I think that they should also be added in this PR).

Can we instead create a base class out of existing testcase? And then create three subclasses which would look like so:

class GetattrSuggestionsTests(BaseSuggestionsTests, unittest.TestCase):
    def get_suggestion(self, obj, name):
        # get suggestions using `getattr`

class SetattrSuggestionsTests(BaseSuggestionsTests, unittest.TestCase):
    def get_suggestion(self, obj, name):
        # get suggestions using `setattr`

# the same for `delattr`

[Pranjal095]

I'll first refactor the tests as per your suggestion, and keep that as a separate commit.
I was unsure of adding setattr suggestion tests to this PR because:

1. The concerning issue was raised for adding delattr suggestions alone.
2. There are multiple ways to simulate an AttributeError for setattr (custom __slots__, @property etc.), and I felt it would be better to discuss the appropriate testing mechanism in a separate PR.

[Pranjal095]

I have made the requested changes as per the refactor request. Kindly review the PR again.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[picnixz]

I also don't think that merging a fix with tests into one PR is a good idea

I would have actually expected that to be a feature and not a fix actually!

When we have a fix and new tests - we usually merge them as different PRs, that's the first time I see that we combine PRs

I actually always combined my fixes with my tests to check indeed that my fix is correct. Same for features.