ci: add pre-commit hook

[bingryan]

Description

add git pre-commit hook

Usage

step1: install pre-commit for you local repo

just git-pre-commit

step2: auto format submitted **.rs files for your git commit xxxx

[bingryan]

After several PRs, i sometimes submit some unformatted code, then get CI lint error. i think add pre-commit hook is useful for this case.

[bingryan]

@casey I don't know if this is a necessary PR, I think If format and test can be performed before each commit. it will reduce some unnecessary CI time

[raphjaph]

Suggested change

	cargo fmt --all
	git add -- $(echo "$files" | paste -s -d " " -)
	cargo fmt --check

[bingryan]

This only automatically formats the submitted rust file.

for only cargo fmt --check, if there are unformatted files, you will need to execute cargo fmt --all and then git add xxx again.

[raphjaph]

I think we don't want to add anything and only check formatting,

[bingryan]

only format the submitted Rust file now

[raphjaph]

It's not a good idea to change files in a pre-commit hook. So we only want to check things not write to any files

[raphjaph]

lgtm

Made it very simple and generic for now, we can add more complex hooks later.