[flake8-pyi] Fix more complex cases (PYI019)

[InSyncWithFoo]

Summary

Resolves #15798.

PYI019 is now a binding-based rule. All references to the type variable will now be replaced correctly. As a result, the fix is now safe in most cases; when that is not possible, its applicability remains display-only. Additionally, for a safe fix, comments within the fix ranges will cause it to be marked as unsafe.

Test Plan

cargo nextest run and cargo insta test.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[AlexWaygood]

I'd like for us to fix existing bugs such as #15849 first before extending this rule further (edit: see #15851, and #15853)

[AlexWaygood]

Previously, there was also a small bug that would cause a PEP 695 type variable not to be removed correctly were it to be placed at the very end of the type parameter list. This has been fixed as well.

Could you possibly separate this out into an isolated PR? That would make it easier to see which tests are specifically for this bugfix

[InSyncWithFoo]

@AlexWaygood I submitted #15854. As it happens, this PR overlaps with #15853 as well. I'll rebase this once you give the heads-up.

[AlexWaygood]

I'll rebase this once you give the heads-up.

Okay, I'm done -- rebase at your leisure! Thanks :-)