build: add nix flake for linting + devShell + workflow

[mrcjkb]

I noticed there's a stylua run in the makefile, but there's no .stylua.toml.

• That should probably be added before this gets merged.

This adds a Nix flake with:

• A devShell with things like lua-language-server, luacheck, stylua, ...
• checks that run the linters (I also included editorconfig-checker, but I'm not sure if we want that?).
• A GitHub workflow that runs the checks on push and PR.

If we decide to merge this, I would like to follow-up with a check that runs busted tests using neorocksTest.

[mrcjkb]

Note: When run locally, the stylua check fails.

[mrcjkb]

Oh wait - there is a stylua.toml (not hidden) 🤔 I wonder why it's failing...

Update: I think it's nio. I've added a .styluaignore, but it seems like stylua doesn't pick up on it if you pass in the file name, which is what the pre-commit-hooks-nix check does.

See also: JohnnyMorganz/StyLua#751

[vhyrro]

It's likely because you're not compiling stylua with 5.2 support, which is required for parsing of goto and some other stuff. With cargo it's as simple as cargo install stylua --features lua52 but unsure how it works in nix.

[vhyrro]

Also a stylua.toml is also considered standard and it picks it up on my end with no problems 🤔

[mrcjkb]

Let's see if the fix gets merged on the Nix side: cachix/git-hooks.nix#346
The stylua behaviour is intended.