[perflint] Handle tuples in dictionary comprehensions (PERF403)

[liortct]

This pull request fixes the bug described in issue #19153.

The issue occurred when PERF403 incorrectly flagged cases involving tuple unpacking in a for loop. For example:

def f():
    v = {}
    for (o, p), x in [("op", "x")]:
        v[x] = o, p

This code was wrongly suggested to be rewritten into a dictionary comprehension, which changes the semantics.

Changes in this PR:

Updated the PERF403 rule to correctly handle tuple unpacking in loop targets.

Added regression tests to ensure this case (and similar ones) are no longer flagged incorrectly.

Why:
This ensures that PERF403 only triggers when a dictionary comprehension is semantically equivalent to the original loop, preventing false positives.

[liortct]

@ntBre
Hello 👋 just a gentle reminder about this PR. I’d be happy to make any changes if needed. Thanks for reviewing when you get the chance!

[ntBre]

Thank you! I'll try to get to it this week :)

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[ntBre]

Thank you, this looks great! I just had a few small suggestions.

[liortct]

@ntBre
Thanks a lot for the review and comments!
I’ve addressed all the issues, and the PR is ready for another review.
If there’s anything else that needs to be adjusted, please let me know and I’ll update it promptly.

Thanks again!

[ntBre]

Thank you!