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