Add a system hook for people who don't have the rust toolchain

[IamTheFij]

This PR will add back the option for a system pre-commit hook. Otherwise every update will require cargo and the rust tool chain, which some Lua developers may not have and may prefer to install their own binary.

One downside to system hooks is that the version tag is really irrelevant as it won't update the checker.

Another option would be to do something like this: https://github.com/shellcheck-py/shellcheck-py and provide a wrapper. This example uses Python to manage the download and installation. Since this person has put this in it's own repo, they are hard coding the version and sha's.

I'm tempted to write a Python package that can accept a git repo as an argument and then it will download the release using repo metadata (reading Cargo.toml) and then execute that binary. This would be helpful, not just for StyLua, but any statically compiled checkers that have dependencies.

[JohnnyMorganz]

Thanks!

[gegoune]

So how could this system version be used?

[JohnnyMorganz]

So how could this system version be used?

I assume something like this: (disclaimer, i haven't actually tested this):

repos:
-   repo: https://github.com/johnnymorganz/stylua
    rev: v0.11.3
    hooks:
    -   id: stylua-system

Changing stylua-system with stylua would use the cargo toolchain instead

[gegoune]

Getting this:

$ pre-commit
[INFO] Initializing environment for https://github.com/johnnymorganz/stylua.
[ERROR] `stylua-system` is not present in repository https://github.com/johnnymorganz/stylua.  Typo? Perhaps it is introduced in a newer version?  Often `pre-commit autoupdate` fixes this.
$ pre-commit autoupdate
Updating https://github.com/johnnymorganz/stylua ... Cannot update because the update target is missing these hooks:
stylua-system
$

[gegoune]

It works for rev: master so I assume it wasn't part of release?

[IamTheFij]

Yea, I think the release was cut before this was merged.