Add the ability to create a makeshift Arch Linux repository in GitHub releases

[loathingKernel]

The goal of this PR is to add the necessary bits to generate the files (<reponame>.{db,db.tar.gz,files.file.tar.gz}) that constitute an Arch Linux repository.

The way it works is by updating the repository files and exposing them in the action outputs to be uploaded. It also allows for custom pacman and makepkg configuration files to pull dependencies from releases.

You can see it in use in my own repo here https://github.com/loathingKernel/PKGBUILDs

I am opening this as a draft to see if there is any interest in merging it and as a RFC. If this is something that could be included, I am will update the documentation too to reflect the changes.

The yay -> paru change or downloading it from alerque repository are not mandatory and I will exclude them from the final PR if they are not wanted.

[edlanglois]

Thank you for the PR! I'm open to including it but I can't promise a quick review. I mostly don't maintain this project any more and I've never tried creating an arch repo so I'm not familiar with the changes you're proposing.

[loathingKernel]

Sorry for the lack of communication or a reply even. I have been testing the workflow with my makeshift repository since the PR was opened. I've been trying to identify problems through usage. It has been quite stable so far, but there are some outstanding issues and TODOs, at least for my repository oriented workflow.

• There is no package signing, I haven't done it before but I think it would be a good inclusion. I will look at this once I have some time available.
• Minor: There is no way to create the initial database from the action, and the action requires to download it. This might make the action unnecessarily complicated and can be fixed through documentation.
• Minor: There is no way to remove a package from the database/repository by using the action. This also can be fixed through documentation or a separate action.