Code and project formatting

[Beakerboy]

• Removed commented-out code
• Formatted whitespace to PEP8
• Added checks to ensure PEP8 naming
• Fully typehinted
• Moved sources to /src and tests to /tests
• Added pyproject.toml

[Beakerboy]

This is the first of several PRs I would like to submit. Let me know if you are willing to accept pull requests. This just restructures the codebase and improves the linting of the code. There are no breaking changes to the code: tests remain unchanged.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (7839c1f) 100.00% compared to head (0177666) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 1 1 Lines 273 276 +3 ========================================= + Hits 273 276 +3 ``` | [Impacted Files](https://codecov.io/gh/emilydolson/python-red-black-trees/pull/2?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Emily+Dolson) | Coverage Δ | | |---|---|---| | [src/rbtree.py](https://codecov.io/gh/emilydolson/python-red-black-trees/pull/2?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Emily+Dolson#diff-c3JjL3JidHJlZS5weQ==) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Emily+Dolson). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Emily+Dolson)

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[emilydolson]

Thanks! I am happy to accept pull requests and these look like good changes!