lifecycle: simplify the review process

This revamps significantly the review process and changes some of the criteria:

• Adds a focus on "do what you can", and tries to be non-technical, provides more hints on where to find the information.
• Removes some clutter ("tip: read the Table of contents" is not useful, and no need to join the Gitlab Project, assign yourself an issue, etc)
• Moves the suggested items to a separate section
• Adds a criteria that an extension should report more than 25 installs.
  • For me, this has always been a quality signal.
  • And since review resources are limited, we should focus on extensions that have reached a certain threshold. Having an extension reviewed should not be the first step to promote an extension. Authors can post on Stack Exchange, blog posts, etc.
  • On the flip side: we should make it possible to install any extension in-app, as long as the status is clear.