Fix syntax error false positives for escapes and quotes in f-strings

[ntBre]

Summary

Fixes #20844 by refining the unsupported syntax error check for PEP 701
f-strings before Python 3.12 to allow backslash escapes and escaped outer quotes
in the format spec part of f-strings. These are only disallowed within the
f-string expression part on earlier versions. Using the examples from the PR:

>>> f"{1:\x64}"
'1'
>>> f"{1:\"d\"}"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: Invalid format specifier '"d"' for object of type 'int'

Note that the second case is a runtime error, but this is actually avoidable if
you override __format__, so despite being pretty weird, this could actually be
a valid use case.

>>> class C:
...     def __format__(*args, **kwargs): return "<C>"
...
>>> f"{C():\"d\"}"
'<C>'

At first I thought narrowing the range we check to exclude the format spec would
only work for escapes, but it turns out that cases like f"{1:""}" are already
covered by an existing ParseError, so we can just narrow the range of both our
escape and quote checks.

Our comment check also seems to be working correctly because it's based on the
actual tokens. A case like this:

f"""{1:# }"""

doesn't include a comment token, instead the # is part of an
InterpolatedStringLiteralElement.

Test Plan

New inline parser tests

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[amyreese]

LGTM

[MichaReiser]

Thank you