Sanitize the optional dependencies for spider API

Only return unread notifications

Make get_unread_push_actions_for_user_in_range only return unread event actions, being more true to its name. Done in two separate sql queries to get actions after a read receipt and those in a room wiht no receipt at all. SQL queries by Erik.

Don't return empty public rooms

Don't auto log failed auth checks

Add get endpoint for pushers

Decodes pushers rows on the main thread rather than the db thread and uses _simple_select_list. Also do the same to the function I copied and factor out the duplication into a helper function.

Check if we've already backfilled events

As per https://github.com/matrix-org/matrix-doc/pull/308

Change pushers to use the event_actions table

and wrap unsafe process in a try block