Use dynamic site URL to allow secure tunnels

[sejas]

Related issues

• Fixes https://github.com/Automattic/dotcom-forge/issues/9783

Proposed Changes

• Set WP_SITEURL and WP_HOME as mu plugin
• Our goal is that using a secure tunnel as ngrok we could use Jetpack in online mode.

The new upload images are still uploaded with the localhost:8881 domain

Testing Instructions

• Run npm start
• Make sure existing sites work as expected
• Create a new site
• Confirm it works as expected
• Access http://whatever.localhost:8881 and confirm it works as expected
• Run ngrok http 8881 where the port is what the site uses by default
• Open the ngrok link observe the site opens correctly and you can navigate through the pages
• The links and images saved in the database don't change pointing to localhost

studio-ngrok2.mp4

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[sejas]

Testing with empty Studio sites I got an infinite redirection when trying to access /wp-admin. This redirection does not happen when loading Alexa's site that I pulled from WPcom.