Add new rule to check for useless quote escapes

[ThiefMaster]

When using the autofixer for Q000 it does not remove the backslashes from quotes that no longer need escaping.
This new rule checks for such backslashes (regardless whether they come from the autofixer or not) and can remove them.

I used Q100 to avoid ocnflicts with Q00x rules flake8-quotes might add (even though it's not very actively maintained)

fixes #8617

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+1 -0 violations, +0 -0 fixes in 41 projects)

sphinx-doc/sphinx (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --preview

+ tests/test_ext_inheritance_diagram.py:219:16: Q004 [*] Unnecessary escape on inner quote character

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
Q004	1	1	0	0	0

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[charliermarsh]

Haven't reviewed the code yet, but the ecosystem check seems to be flagging some cases like "\\'", in which the backslash escapes are necessary (I think?) to add a backslash literal.

[ThiefMaster]

Yeah, just noticed that I'm not checking for escaped backslashes - already on it

[charliermarsh]

Awesome, thanks @ThiefMaster!

[ThiefMaster]

Ecosystems looks much better now. The one new violation is actually correct since those quotes there should not be escaped.

[ThiefMaster]

The mkdocs CI failure seems unrelated (it didn't fail until I rebased to the latest master).