Implement flake8-commas (#1872)

Implements [flake8-commas](https://github.com/PyCQA/flake8-commas). Fixes #1058.

The plugin is mostly redundant with Black (and also deprecated upstream), but very useful for projects which can't/won't use an auto-formatter. 

This linter works on tokens. Before porting to Rust, I cleaned up the Python code ([link](https://gist.github.com/bluetech/7c5dcbdec4a73dd5a74d4bc09c72b8b9)) and made sure the tests pass. In the Rust version I tried to add explanatory comments, to the best of my understanding of the original logic.

Some changes I did make:

- Got rid of rule C814 - "missing trailing comma in Python 2". Ruff doesn't support Python 2.
- Merged rules C815 - "missing trailing comma in Python 3.5+" and C816 - "missing trailing comma in Python 3.6+" into C812 - "missing trailing comma". These Python versions are outdated, didn't think it was worth the complication.
- Added autofixes for C812 and C819.

Autofix is missing for C818 - "trailing comma on bare tuple prohibited". It needs to turn e.g. `x = 1,` into `x = (1, )`, it's a bit difficult to do with tokens only, so I skipped it for now.

I ran the rules on cpython/Lib and on a big internal code base and it works as intended (though I only sampled the diffs).

README.md

@@ -123,6 +123,7 @@ of [Conda](https://docs.conda.io/en/latest/):
    1. [pygrep-hooks (PGH)](#pygrep-hooks-pgh)
    1. [Pylint (PLC, PLE, PLR, PLW)](#pylint-plc-ple-plr-plw)
    1. [flake8-pie (PIE)](#flake8-pie-pie)
+   1. [flake8-commas (COM)](#flake8-commas-com)
    1. [Ruff-specific rules (RUF)](#ruff-specific-rules-ruf)<!-- End auto-generated table of contents. -->
 1. [Editor Integrations](#editor-integrations)
 1. [FAQ](#faq)
@@ -1129,6 +1130,16 @@ For more, see [flake8-pie](https://pypi.org/project/flake8-pie/0.16.0/) on PyPI.
 | PIE794 | DupeClassFieldDefinitions | Class field `...` is defined multiple times | 🛠 |
 | PIE807 | PreferListBuiltin | Prefer `list()` over useless lambda | 🛠 |
 
+### flake8-commas (COM)
+
+For more, see [flake8-commas](https://pypi.org/project/flake8-commas/2.1.0/) on PyPI.
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| COM812 | TrailingCommaMissing | Trailing comma missing | 🛠 |
+| COM818 | TrailingCommaOnBareTupleProhibited | Trailing comma on bare tuple prohibited |  |
+| COM819 | TrailingCommaProhibited | Trailing comma prohibited | 🛠 |
+
 ### Ruff-specific rules (RUF)
 
 | Code | Name | Message | Fix |

licenses/LICENSE_PyCQA_flake8-commas

@@ -0,0 +1,45 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 Thomas Grainger.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+
+Portions of this flake8-commas Software may utilize the following
+copyrighted material, the use of which is hereby acknowledged.
+
+Original flake8-commas: https://github.com/trevorcreech/flake8-commas/commit/e8563b71b1d5442e102c8734c11cb5202284293d
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.