Added blueprint for showcasing custom plugin

[Lovor01]

This is more elaborate example, which shows how to upload media files, plugin and theme from own server and how to set the basic starting options to showcase plugin. WXR is used for importing content. There is also a readme file with explanations.

[github-actions]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Some things to be aware of

• The Plugin and Theme Directories cannot be accessed within Playground.
• All changes will be lost when closing a tab with a Playground instance.
• All changes will be lost when refreshing the page.
• A fresh instance is created each time the link below is clicked.
• Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance,
  it's possible that the most recent build failed, or has not completed. Check the list of workflow runs to be sure.

For more details about these limitations and more, check out the Limitations page in the WordPress Playground documentation.

Test this pull request with WordPress Playground.

[bgrgicak]

Would it be possible to use paths from this GitHub repo or at least WordPress.org?

In case something changes with the domain, we would still like for the blueprint to work.

[Lovor01]

Ok, I'll rewrite blueprint as soon as I can.

[bph]

@Lovor01 Let me know how we can help getting your blueprint into the gallery. Are there any blockers (apart from time) we can assist you with?

[Lovor01]

Birgit, thank you for bringing this up. There are no other blockers, except my time. I will try to make this priority and finish this week.

[Lovor01]

I updated blueprints and uploaded required files, it should work now with github hosted files. I also improved readme file to instruct reader how he can replicate and modify this solution for his needs. Please let me know if anything else is a problem to merge this.