Initial ActivityPub investigation

[mperham]

We'll need a core set of models before we can show any functionality. ActivityPub influences these models massively so we'll need to hammer out the various AP entities and how they translate into database tables. For instance, Notes are Created by an Actor who is a Person. A Person is a local or remote user identified by a URL.

• Review the AP links below
• Create further issues for necessary models and APIs

https://docs.joinmastodon.org/spec/activitypub/
https://socialhub.activitypub.rocks/pub/guide-for-new-activitypub-implementers