When fetching the list of tables from the postgres database during the
db port, it is assumed that the tables are in the public schema. This is
not always the case, so lets just rely on postgres to determine the
default schema to use.

Implement no op for room stream in sync

Add fallback to last_active_ts if it beats the last sync time on a presence timeout.

Format presence events on the edges instead of reformatting them multiple times

Handle PartialDownloadError in CAS login

Fix assertion to stop transaction queue getting wedged

... and update some docstrings to correctly reflect the types being used.

get_new_device_msgs_for_remote can return a long under some circumstances,
which was being stored in last_device_list_stream_id_by_dest, and was then
upsetting things on the next loop.

Add some metrics on notifier

Phone number registration / login support v2

Fix routing loop when fetching remote media

Reduce number of spurious sync result generations.

Speed up public room list

- don't blindly proxy all HTTPRequestExceptions
- log unexpected exceptions at error
- avoid `isinstance`
- improve docs on `from_http_response_exception`

Give CodeMessageException back its `msg` attribute, and use that to hold the
HTTP status message for HttpResponseException.

Fix current_state_events table to not lie

If we try and persist two state events that have the same ancestor we
calculate the wrong current state when persisting those events.

Implement delete_devices API

(But this doesn't implement the same for deleting access tokens or e2e keys.

Also respond to code review.

Only offer msisdn flows if the x_show_msisdn option is given.

Changes from https://github.com/matrix-org/synapse/pull/1971