Only notify for messages in one to one rooms, not every event

Fixes the fact that candidate events and hangups generated notifications.

Add missing yield in push_rules set enabled

Move some sync logic from rest to handlers pacakege

Implement a `_simple_select_many_batch`

Push: Use storage apis that are cached

Add index to event_push_actions

Underscores are allowed in user ids

Better fix for actions with both dont_notify and tweaks

Don't add notifications to the table unless there's actually a 'notify' action

Overlay the push_rules_enabled map for users

Overlay the push_rules_enabled map for users, otherwise they won't be able to disable server default rules.

Make LRU caching tree-based so subtrees of the cache can be invalidated cheaply.

Use new invalidate_many cache invalidation to invalidate the event_push_actions cache appropriately.