Suggest adding command line args support for command like git clone.
For now I found we just invoke git clone in #'quelpa-build--checkout-git, and I think it could be good if we can add extra command line args for git clone, at least under the following two circumstances:
- if we don't care the repo history, we can use --depth 1
- if we just need to use a subdirectory of the whole repo, for example: https://github.com/lilypond/lilypond, we can use --filter
In other words, in most case, it's too heavy to clone the whole repo and its history, so we need a variable for the quelpa user to specify their own args.