[`flake8-comprehensions`] Handle trailing comma in fixes for `unnecessary-generator-list/set` (`C400`,`C401`) (#15929)
The unsafe fixes for the rules [unnecessary-generator-list
(C400)](https://docs.astral.sh/ruff/rules/unnecessary-generator-list/#unnecessary-generator-list-c400)
and [unnecessary-generator-set
(C401)](https://docs.astral.sh/ruff/rules/unnecessary-generator-set/#unnecessary-generator-set-c401)
used to introduce syntax errors if the argument to `list` or `set` had a
trailing comma, because the fix would retain the comma after
transforming the function call to a comprehension.
This PR accounts for the trailing comma when replacing the end of the
call with a `]` or `}`.
Closes #15852