Build a zip file when creating a new release on GitHub, then upload it.

[Hug0-Drelon]

What?

All is in the title.

How?

• Create a new workflow to build and upload the zip corresponding to the new release. Zip build also available on demand but without release upload.
  • Set up Node and PHP, then install production dependencies.
  • Uses 10up/action-wordpress-plugin-deploy to build the zip.
  • Upload zip from the created artifact to the release assets if current event allows it.
• Add a .distignore to remove unwanted files from the zip.

Note: for now the workflow doesn't commit to the SVN repo, this is a first step to create a release before updating wp.org.