Add Theme Review Environment

[supernovia]

Aiming to make this contribution pathway easier:
https://make.wordpress.org/handbook/pathways/design/review-themes/

Noting I installed the old theme check content. Not sure yet if there's something better for testing FSE themes, but if I find out, I'll fix it :)

[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

• 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.

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

[akirk]

This is great! Just noting that your PR also contains an example blueprint hello-blueprints, is this intentional?

Also, I'm wondering, would something like https://akirk.github.io/playground-step-library/?example=theme-review-environment could also work for this use case? Where you have a preconfigured blueprint and you just enter the theme slug and then press "Launch in Playground"?

[supernovia]

Oh! This PR was mostly for Theme Review. I didn't mean to include Hello Blueprints, but if it's OK to add and looks useful here, great.

Also, I'm wondering, would something like https://akirk.github.io/playground-step-library/?example=theme-review-environment could also work for this use case? Where you have a preconfigured blueprint and you just enter the theme slug and then press "Launch in Playground"?

Good question! I've not reviewed themes myself yet. For now, we just wanted a standard "here are the plugins you'll need" blueprint to simplify reviewing themes -- from there they're likely to install a few different themes during one test session.