Use room_stats and room_state for room directory search

We have set the max retry interval to a value larger than a postgres or
sqlite int can hold, which caused exceptions when updating the
destinations table.

To fix postgres we need to change the column to a bigint, and for sqlite
we lower the max interval to 2**62 (which is still incredibly long).

Fetching a censored redactions caused an exception due to the code
expecting redactions to have a `redact` key, which redacted redactions
don't have.

Fixes #5905

If email or msisdn verification aren't supported, let's stop advertising them
for registration.

Fixes #6100.

Pull the checkers out to their own classes, rather than having them lost in a
massive 1000-line class which does everything.

This is also preparation for some more intelligent advertising of flows, as per #6100

because, frankly, it looked like it was written by an axe-murderer.

This should be a non-functional change, except that where `m.login.dummy` was
previously advertised *before* `m.login.terms`, it will now be advertised
afterwards. AFAICT that should have no effect, and will be more consistent with
the flows that involve passing a 3pid.

This is a) simpler than querying user_ips directly and b) means we can
purge older entries from user_ips without losing the required info.

The storage functions now no longer return the access_token, since it
was unused.

Track the time that a server started failing at, for general analysis purposes.

This allows support users to be created even on MAU limits via
the admin API. Support users are excluded from MAU after creation,
so it makes sense to exclude them in creation - except if the
whole host is in disabled state.

Signed-off-by: Jason Robinson <jasonr@matrix.org>

Co-Authored-By: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

Previously if the first registered user was a "support" or "bot" user,
when the first real user registers, the auto-join rooms were not
created.

Fix to exclude non-real (ie users with a special user type) users
when counting how many users there are to determine whether we should
auto-create a room.

Signed-off-by: Jason Robinson <jasonr@matrix.org>

Previously the stats were not being correctly populated.

Python will return a tuple whether there are parentheses around the returned values or not.

I'm just sick of my editor complaining about this all over the place :)

Template config files

* Imagine a system composed entirely of x, y, z etc and the basic operations..

Wait George, why XOR? Why not just neq?

George: Eh, I didn't think of that..

Co-Authored-By: Erik Johnston <erik@matrix.org>

Get rid of the labyrinthine `recoverer_fn` code, and clean up the startup code
(it seemed to be previously inexplicably split between
`ApplicationServiceScheduler.start` and `_Recoverer.start`).

Add some docstrings too.

This refactors MatrixFederationAgent to move the SRV lookup into the
endpoint code, this has two benefits:
	1. Its easier to retry different host/ports in the same way as
	   HostnameEndpoint.
	2. We avoid SRV lookups if we have a free connection in the pool

If we have recently seen a valid well-known for a domain we want to
retry on (non-final) errors a few times, to handle temporary blips in
networking/etc.

This gives a bit of a grace period where we can attempt to refetch a
remote `well-known`, while still using the cached result if that fails.

Hopefully this will make the well-known resolution a bit more torelant
of failures, rather than it immediately treating failures as "no result"
and caching that for an hour.