New “Bridgetown Center” Plugin Program

[jaredcwhite]

We would like to completely revamp our plugin directory and institute a mentorship program to encourage the development of new Bridgetown plugins & themes. We are inspired by initiatives in other ecosystems such as GNOME Circle.

This is an "epic" style issue to track the progress of a few interrelated efforts:

1. Design a brand-new Plugins directory which sources content from a new "plugins" collection in our website repo. This would replace our previous practice of scraping GitHub for repos with a particular tag. By managing the content in our repo, people will be able to submit new plugin information which can be hosted on GitHub, Codeberg, and other forges, plus include more information than we could glean simply from GitHub metadata.
2. Make a distinction between plugins submitted by the community at large, and a publicized Bridgetown Center program where plugins by first & third-party developers are promised to be kept up-to-date with new Bridgetown releases and reasonably responsive to feature/bugfix requests. Existing plugins such as bridgetown_sequel would be listed here, for example.
3. Set up documentation and a process for people to be mentored by the Bridgetown Core Team and aided in bringing their plugins into the Center program.
4. Review existing documentation and sample code regarding how to develop plugins/themes to make sure we have high-quality reference material.