Sets up a generic atproto module to store atproto implementation. Mainly
doing this so that I can switch between rsky/atrium as well as add my
own layers on top.
This also switches the old Xrpc/Router use of Nsid to the atproto api
implementation of it. Next up is the DB where I'll need a bunch of
these.
Adds an interface for adding xrpc queries and procedures that is a bit
simpler than directly interfacing with axum. Should provide good
scaffolding for next steps.
