FEP-3b86: Activity Intents

[benpate]

Is your feature request related to a problem? Please describe.
Sharing and liking pages on remote servers is difficult with ActivityPub/Fediverse software. If I'm browsing the open web and I find something I like, there's no easy way to get back to my home server except for copying/pasting the URL. Good luck on mobile devices.

Describe the solution you'd like
FEP-3b86: Activity Intents is a small change to the data published by WebFinger that would improve how Bookwyrm connects to other Fediverse servers.

Describe alternatives you've considered
It is similar to the old oStatus "remote follows" but it is 1) works for any kind of Activity, not just Follow, and 2) has actual documentation.

Additional context
Implementing this FEP is as simple updating WebFinger results to include the URLs that let website visitors perform Activities on their own server (such as Follow, Like, or Announce). Then, other websites can use this information to display interactive buttons to take those actions.

I am not a Python developer, so I probably shouldn't try to make this change to Bookwyrm myself, but I'm happy to work with anyone who's interested in making this enhancement.