Add two ratelimiters on login (per-IP address and per-userID).

Split TransactionQueue up

Move client receipt processing to federation sender worker.

Allow passing --daemonize to workers

This setup is a way to manage workers with systemd. It does however not
require workers. You can use this setup without workers. You just have
to make sure that the homeserver is forking and writes its PID file
to the location the service is looking in.

The currently distributed setup in the debian package does not work in
conjunction with workers.

* Adds changelog

* Lets systemd handle the forking

Sets all services to `type=simple` and disables daemonizing on the
synapse side.

* Formats readme to 80 columns per line

* Allows for full restart of all workers

* Changes README to reflect the new setup

* Adds dot to end of changelog file

* Removes surplus word

Co-Authored-By: targodan <targodan@users.noreply.github.com>

* Adds missing word

Co-Authored-By: targodan <targodan@users.noreply.github.com>

* Fixes linebreak

Co-Authored-By: targodan <targodan@users.noreply.github.com>

* Fixes unit type

* Add some stuff back to the .gitignore

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Add changelog

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Reorder and remove old items from .gitignore

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Revert "Make federation endpoints more tolerant of trailing slashes for some endpoints"

This reverts commit 290552fd.

Improve searching in the userdir

This is easier than having to have a million fields keyed on destination.

This is mostly a prerequisite for #4730, but also fits with the general theme
of "move everything off the master that we possibly can".

I'm going to use this in queues and things, so it'll be useful to give it more
of a structure.

Transfer push rules (notifications) on room upgrade

Improved federation configuration docs.  Specifically detailing  .well-known and SRV based delegation methods. 

Inspiration Valentin Lab <valentin.lab@kalysto.org> for https://github.com/matrix-org/synapse/pull/4781

* Clarify what registration_shared_secret allows for (#2885)

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Add changelog

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Server side of a solution towards #3622.

Correctly log expected errors when fetching server keys