Basic ActivityPub webfinger/actor support

Alex Gleasonrequested to merge
alexgleason/engine:webfinger into master

Related: minds#90 (closed)

This MR exposes basic ActivityPub actors which can be looked up through webfinger. The result looks something like this from the Fediverse (minds.ngrok.io is a Minds server):

gleasonator.com__alex_minds.ngrok.io

Merge request reports