Refactor the comment handling of a statement's last expression

[MichaReiser]

Summary

This refactor simplifies implementing #6975. I also find it easier to understand where this layout is used because the explicit calls in the assignment formatting compared to inside (anyway complicated) maybe_parenthesize function.

Test Plan

cargo test

The similarity index remains unchanged

project	similarity index	total files	changed files
cpython	0.75804	1799	1648
django	0.99984	2772	34
home-assistant	0.99963	10596	146
poetry	0.99925	317	12
transformers	0.99967	2657	322
twine	1.00000	33	0
typeshed	0.99980	3669	18
warehouse	0.99977	654	13
zulip	0.99970	1459	21

[MichaReiser]

Current dependencies on/for this PR:

• main
  • PR Refactor the comment handling of a statement's last expression #8920 👈
    • PR prefer_splitting_right_hand_side_of_assignments preview style #8943
      • PR Implement Black's parenthesize-long-type-hints preview style #9102
    • PR Inline trailing comments for type alias similar to assignments #8941
      • PR Ignore the open parentheses when measuring BestFitsParenthesize #8940

This stack of pull requests is managed by Graphite.

[github-actions]

ruff-ecosystem results

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.