[refurb] implement hardcoded-string-charset (FURB156)

[alex-700]

Summary

Implement hardcoded-string-charset (FURB156)
See:

• Support for refurb #1348
• original lint

Test Plan

cargo test

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+3 -0 violations, +0 -0 fixes in 2 projects; 52 projects unchanged)

apache/airflow (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ dev/breeze/src/airflow_breeze/utils/packages.py:433:48: FURB156 [*] Use of hardcoded string charset

bokeh/bokeh (+2 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ examples/reference/models/Text.py:9:5: FURB156 [*] Use of hardcoded string charset
+ tests/unit/bokeh/util/test_token.py:69:20: FURB156 [*] Use of hardcoded string charset

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
FURB156	3	3	0	0	0

[MichaReiser]

Thanks. This looks great.

I left a few smaller comments. It would also be great to add some documentation to Charset and bitset, considering that the representations are non-trivial and make some assumptions about how they're used.

[MichaReiser]

Nice, thanks for following up. Let's add a test for when the expression is parenthesized to verify that the fix is correct (if not, take a look at parenthesized_range.

I also think that we may be able to remove the factory methods on AsciiCharSet and reduce them to just one.

[MichaReiser]

Nice thanks. This looks great!