Support batch updates in the worker sender 

Improve ratelimit on registration

This reverts commit d7dbad35.

 Add 'server_version' endpoint to admin API

* Rate-limiting for registration

* Add unit test for registration rate limiting

* Add config parameters for rate limiting on auth endpoints

* Doc

* Fix doc of rate limiting function

Co-Authored-By: babolivier <contact@brendanabolivier.com>

* Incorporate review

* Fix config parsing

* Fix linting errors

* Set default config for auth rate limiting

* Fix tests

* Add changelog

* Advance reactor instead of mocked clock

* Move parameters to registration specific config and give them more sensible default values

* Remove unused config options

* Don't mock the rate limiter un MAU tests

* Rename _register_with_store into register_with_store

* Make CI happy

* Remove unused import

* Update sample config

* Fix ratelimiting test for py2

* Add non-guest test

Remove reference to that no longer exists in README

Remove unnecessary dollar signs

Stop backpaginating when events not visible

Clean ups in replication notifier

 Allow /keys/{changes,query} API to run on worker

Add some debug about processing read receipts.

Clean up read-receipt handling.

Both (!) things that register as replication listeners do the right thing wrt
logcontexts, so this is redundant.

I guess this was used once? It's not now, anyway.

I'm hoping to establish which rooms are having lots of RRs sent for them, and
how old the events are when they are sent.

Remove a call to run_as_background_process: there is no need to run this as a
background process, because build_and_send_edu does not block.

We may as well inline the whole of _push_remotes.

A dollar sign is already appended to the end of each PATH, so there's
no need to add one in the PATH declaration as well.

When filtering events to send to server we check more than just history
visibility. However when deciding whether to backfill or not we only
care about the history visibility.

The v4v6 option only has a usage one ipv6 socket: https://serverfault.com/q/747895



Signed-off-by: Flakebi <flakebi@t-online.de>