Enhance playground PR previews

[carstingaxion]

Description of the Change

This PR adds some minor enhancements to the - now almost, almost, almost ready - Pull request playground previews:

• Run the time & ressource intensive build-step only if the changed files require that really
• Set “Add a new event post” as landing page for the playgrounds
• Set php version to 8.2 and wp version to latest
• Run in network mode (to allow the download of additional plugins or themes)
• Setup as WordPress Multisite

Closes # Testing & Clean-up after #666 & #741

How to test the Change

Changelog Entry

Changed - …

Credits

Props @carstingaxion

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[what-the-diff]

PR Summary

• Deletion of "permissions" block in config file
  The "permissions" segment from the config file .github/workflows/playground-preview.yml has been removed. This change may alter how the system responds to certain user interactions with the playground preview feature.

[carstingaxion]

Bingo @mauteri !

Now, it's just the plugin-proxy.php which is not in place @MervinHernandez

[carstingaxion]

TESTING: Deletion & re-creation of "Preview changes..." comment

[carstingaxion]

The RESTORED TO TEST (e8967b2) plugin-proxy.php is not recognized. May that be a kind of GitHub caching or is the workflow using the files from the repo instead of the ones from the PR ???

[github-actions]

Preview changes with Playground

You can preview the least recent changes for PR#750 by following one of the links below:

• Normal WordPress playground for PR#750

• Seamless WordPress playground for PR#750

• WordPress playground Builder for PR#750

• Download .zip with build changes

⚠️ Note: The preview sites are created using WordPress Playground. You can add content, edit settings, and test the themes as you would on a real site, but please note that changes are not saved between sessions.

[carstingaxion]

Once again this is such of a type of PRs that can not be tested, without being merged, because of the nature of the pull_request_target.

Even that I said earlier that we should remove the hub.carsten-bach.de/..., I would now vote to keep it for now, to be able to test this PR.

I'll make sure that it gets removed, as soon as all files are in place and running on gatherpress.org.

Can we merge this, please @mauteri ?