build: add GitHub Actions workflow for build and archive

[MaximeMichaud]

Hello,

I have set up a workflow to automatically compress the repository when a commit is made. This workflow only runs on the main branch.

The purpose is to facilitate access to an archive of the plugin for a specific commit, ensuring the archive is identical to the one available on WordPress.org.

Note: actions/upload-artifact does not include hidden files (.) or GitHub-related folders by default.

The only potential improvement for efficiency would be to include certain paths to ensure the workflow doesn't run if no modifications were made to the plugin code.

That said, it's an open-source project, and it's GitHub's servers doing the heavy lifting for free. :)

TL;DR: Added a GitHub Actions workflow to archive the repository on commits to the main branch, matching the archive available on WordPress.org.

[MaximeMichaud]

Forgot to mention that the workflow was tested on a private repository, and everything worked as expected. Ready to be merge ❤️