Introduce mypy, ruff, and pre-commit

[corrylc]

Background

When writing detections for Panther, I would like to use as much python type hinting as possible, while also reducing the bugs that I run into. To enable this, mypy and ruff allow for extensive code quality and type hinting checks.

I am open to breaking this PR up if the ruff/pre-commit portions are not acceptable upstream. While I think they would help with panther-analysis code quality, I don't want them to cause the type hinting improvements to be rejected.

In my experience ruff has totally supplanted pylint/flake8 as the best linting tool for Python as it is a superset of nearly all other tools, and is also radically faster.

Changes

• Applied mypy to panther_base_helpers.py and directly adjacent code until mypy was error free
• Applied ruff to panther_base_helpers.py and directly adjacent code, then modified ruleset to align to Panther code patterns
• Applied ruff-format to panther_base_helpers.py and directly adjacent code
• Introduced pre-commit to run the above tools on the specific files that have been improved
• Added pre-commit to GitHub Actions to enforce the improvements

Questions

• Panther has used inconsistent type hints in many locations, using dict, Mapping, and PantherEvent (rarely) as hints for the event object that gets passed around. While dict is not really appropriate in many cases, it isn't always clear whether Mapping or PantherEvent is the best choice. Open to thoughts here.
• ruff-format is meant to be equivalent to black which is already in use in this codebase. Y'all may want to switch to it in time, since it is much faster, or remove it from this commit if you prefer using black everywhere.
• mypy is not happy that python-core (and to a lesser degree panther_detection_helpers) is not marked as having types. I would be happy to address that, but the repos are not public. Typing those libraries are the best next step.

[arielkr256]

Hey @corrylc sorry for the delay on this! At this point ruff and mypy are core elements of pypanther. I don't think it makes sense to add mypy to panther-analysis, but adding a ruff pre-commit makes a lot of sense. Would you mind updating this to just add ruff?