Add `h-feed` output for subscribing to all events + Return an MF2 content-type for content-type discovery
To make it possible to subscribe to the events using an MF2/Microsub
client we need to expose a new endpoint that returns an h-feed
of all
events.
This will just be the upcoming events (which is the default for Meetup.com's API, although we've set it explicitly), instead of querying Meetup for a lot of extra data.
This requires re-shuffling how the MF2 response for the HEvent
is
returned, replacing that with the MicroformatsResponseContainer
that
returns the right MF2 JSON response.
Closes #2 (closed).