Instead of every time a new email pusher is created, as loading jinja2
templates is slow.

Correctly calculate push rules for member events

Update list cache to handle one arg case

Speed up calculating push rules

We update the normal cache descriptors to handle caches with a single
argument specially so that the key wasn't a 1-tuple. We need to update
the cache list to be aware of this.

Fix invalidation of get_users_with_read_receipts_in_room

Store ActionGenerator in HomeServer

Make get_if_app_services_interested_in_user faster

Make calculating push actions faster

Correct a typo in UPGRADE.rst

Make get_state_groups_from_groups faster.

We add a push rule specific cache that ensures that we can reuse
calculated push rules appropriately when a user join/leaves.

Fix users claimed non-exclusively by an app service don't get notific…

Most of the time was spent copying a dict to filter out sentinel values
that indicated that keys did not exist in the dict. The sentinel values
were added to ensure that we cached the non-existence of keys.

By updating DictionaryCache to keep track of which keys were known to
not exist itself we can remove a dictionary copy.

Make get_joined_users faster when we have delta state