Split out public room list into a worker process

make device IDs more useful for human disambiguation

Fix typo "persiting"

Limit how often we ask for keys from dead servers

Move the E2E key handling into the e2e handler

Add a timeout parameter for end2end key queries.

Add WHERE clause support to index creation

Add a timeout parameter for controlling how long synapse will wait
for responses from remote servers. For servers that fail include how
they failed to make it easier to debug.

Fetch keys from different servers in parallel rather than in series.

Set the default timeout to 10s.

Add is_direct param to /createRoom

Fix backfill when cannot find an event.

`get_pdu` can succeed but return None.

Create new index concurrently

Optimise /notifications query

Fix direct to device messages recieved over federation to notify sync

Add comments to existing schema deltas that used "CREATE INDEX" directly

Revert "Add index to event_push_actions"

Change state fetch query for postgres to be faster

Correctly handle typing stream id resetting

It turns out that postgres doesn't like doing a list of OR's and is
about 1000x slower, so we just issue a query for each specific type
seperately.