Add functions for interacting with git

[yorinasub17]

Description

This implements useful functions for interacting with git in a CLI. These are adapted from our infrastructure-deploy-script python script.

I need this for creating a docker entrypoint script for running steampipe checks in ecs-deploy-runner, which requires cloning the mods.

TODOs

Please ensure all of these TODOs are completed before asking for a review.

• [x] Ensure the branch is named correctly with the issue number. e.g: feature/new-vpc-endpoints-955 or bug/missing-count-param-434.
• [x] Update the docs.
• [x] Keep the changes backward compatible where possible.
• [x] Run the pre-commit checks successfully.
• [x] Run the relevant tests successfully.

[zackproser]

Curious if you've ever played around with https://github.com/go-git/go-git?

[yorinasub17]

Curious if you've ever played around with https://github.com/go-git/go-git?

I have, and was originally going to use it, but I found it to be difficult to navigate around, especially when it comes to all the rules around checking out the "right" version from a ref (which is simplified to git checkout when using the CLI). E.g., see all the logic that kaniko implements to ensure you can clone the repo at the right version: https://github.com/GoogleContainerTools/kaniko/blob/main/pkg/buildcontext/git.go#L58-L139

I would have used this function directly, if it didn't hardcode the checkout dir...

[yorinasub17]

Thanks for review! Merging now.