Add rate-limiting on registration (#4735)

* 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

tests/replication/slave/storage/_base.py

@@ -31,10 +31,10 @@ class BaseSlavedStoreTestCase(unittest.HomeserverTestCase):
         hs = self.setup_test_homeserver(
             "blue",
             federation_client=Mock(),
-            ratelimiter=NonCallableMock(spec_set=["send_message"]),
+            ratelimiter=NonCallableMock(spec_set=["can_do_action"]),
         )
 
-        hs.get_ratelimiter().send_message.return_value = (True, 0)
+        hs.get_ratelimiter().can_do_action.return_value = (True, 0)
 
         return hs