Fix walrus assignment type propagation across call arguments

[Vaishnavi-KN]

Mypy failed to infer the type of a variable assigned via the walrus operator
when the assignment appeared in an earlier keyword argument and the variable
was used in a later argument in the same call.

This PR evaluates call arguments once, left to right, so binder updates from
walrus assignments are preserved.

Fixes #20411

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[A5rocks]

For the test case, please:

• follow test name conventions
• use the inline comments for output

I also recommend using my repro as a test case, maybe separately.

(For some reason I'm unable to make an inline comment...)

[Vaishnavi-KN]

I have updated the test to follow naming conventions and inline output comments as suggested.
The remaining workflows appear to be awaiting maintainer approval.