Implement MSC1915 - 3PID unbind APIs

Make starting pushers faster during start up

Transfers the m.room.related_groups state event on room upgrade.

As requested by @andrewshadura

We start all pushers on start up and immediately start a background
process to fetch push to send. This makes start up incredibly painful
when dealing with many pushers.

Instead, let's do a quick fast DB check to see if there *may* be push to
send and only start the background processes for those pushers. We also
stagger starting up and doing those checks so that we don't try and
handle all pushers at once.

Hopefully this time we really will fix #4422.

We need to make sure that the cache on
`get_rooms_for_user_with_stream_ordering` is invalidated *before* the
SyncHandler is notified for the new events, and we can now do so reliably via
the `events` stream.

test threepid checking

We assume, as we did before, that users bound their threepid to one of
the trusted identity servers. So we simply fill the new table with all
threepids in `user_threepids` joined with the trusted identity servers.

By default the homeserver will use the identity server used during the
binding of the 3PID to unbind the 3PID. However, we need to allow
clients to explicitly ask the homeserver to unbind via a particular
identity server, for the case where the 3PID was bound out of band from
the homeserver.

Implements MSC915.

This changes the behaviour from using the server specified trusted
identity server to using the IS that used during the binding of the
3PID, if known.

This is the behaviour specified by MSC1915.

This will then be used to know which IS to default to when unbinding the
threepid.

start.sh: Fix the --no-rate-limit option for messages

start.sh: Fix the --no-rate-limit option for messages and make it bypass rate limit on registration and login too.

Collect all the things that make room-versions different to one another into
one place, so that it's easier to define new room versions.

Feature/fix small stuff in docker readme.md

Signed-off-by: Jurrie Overgoor <1213142+Jurrie@users.noreply.github.com>

Signed-off-by: Jurrie Overgoor <1213142+Jurrie@users.noreply.github.com>

Combine the CurrentStateDeltaStream into the EventStream

Refactors to replication stream row update/parsing

Remove log line for password.

This PR allows password provider modules to bind email addresses when a user is registering and is motivated by matrix-org/matrix-synapse-ldap3#58

Use event streams to calculate presence

Split up replication.tcp.streams into smaller files