feat(ci): add `pre-commit`

[JaeAeich]

Add precommit, initialize it with necessary checks to keep code change abide by a standard.

Please look at .pre-commit.config for all the hooks that are added.

For reviewer's sake, listing some config that have changed alot of files:

• mdformat, restricting the line length auto fixed multiple files.
• toml-sort, sorted all toml files alphabetically.
• trailing-whitespaces
• end-of-file-fixer

Note: This introduces a discrepancy in the checks between CI and pre-commit, it won't be hard (if someone wanted to) bypass precommit checks and push the code changes. Given adding all the hooks to CI as well might slow CI down, I thinks this discrepancy is the sweet spot. CI has checks for very absolutely necessary checks and pre-commit has some necessary and many nice-to-have checks.

EDIT: THIS pre-commit IS JUST FOR CI, NOT ADDED AS A git HOOK.