Plugin API changes

[deer]

This is a summary of all the plugin API changes, so we don't lose track:

• fix: tailwind supports routes and islands provided by plugins #2266
• Multi plugin islands configs #2275
• feat: add more useful data to plugin render ctx #2224
• feat: allow middleware from plugins to be run before user middleware #2261
• feat: allow plugins to specify static files #2253
• A to-be-created PR that allows plugins to talk to each other. I want my plugin to be able to send a safelist of tailwind classes to the fresh tailwind plugin, so that the user doesn't have to do anything. This is similar to feat: allow plugins to specify static files #2253, in that it removes something the user has to do. (In 2253 the point is to remove the need of creating a style.css file.)
• fix: plugin routes support RouteConfig #2297
• feat: allow plugins to include other plugins #2354

Landing all of these would be a big improvement to the plugin space.