Add a Synapse Module for configuring presence update routing (#9491)

At the moment, if you'd like to share presence between local or remote users, those users must be sharing a room together. This isn't always the most convenient or useful situation though.

This PR adds a module to Synapse that will allow deployments to set up extra logic on where presence updates should be routed. The module must implement two methods, `get_users_for_states` and `get_interested_users`. These methods are given presence updates or user IDs and must return information that Synapse will use to grant passing presence updates around.

A method is additionally added to `ModuleApi` which allows triggering a set of users to receive the current, online presence information for all users they are considered interested in. This is the equivalent of that user receiving presence information during an initial sync. 

The goal of this module is to be fairly generic and useful for a variety of applications, with hard requirements being:

* Sending state for a specific set or all known users to a defined set of local and remote users.
* The ability to trigger an initial sync for specific users, so they receive all current state.

1 files changed, 11 insertions, 10 deletions

diff --git a/tests/handlers/test_sync.py b/tests/handlers/test_sync.py
index e62586142e..8e950f25c5 100644
--- a/tests/handlers/test_sync.py
+++ b/tests/handlers/test_sync.py
@@ -37,7 +37,7 @@ class SyncTestCase(tests.unittest.HomeserverTestCase):
     def test_wait_for_sync_for_user_auth_blocking(self):
         user_id1 = "@user1:test"
         user_id2 = "@user2:test"
-        sync_config = self._generate_sync_config(user_id1)
+        sync_config = generate_sync_config(user_id1)
         requester = create_requester(user_id1)
 
         self.reactor.advance(100)  # So we get not 0 time
@@ -60,7 +60,7 @@ class SyncTestCase(tests.unittest.HomeserverTestCase):
 
         self.auth_blocking._hs_disabled = False
 
-        sync_config = self._generate_sync_config(user_id2)
+        sync_config = generate_sync_config(user_id2)
         requester = create_requester(user_id2)
 
         e = self.get_failure(
@@ -69,11 +69,12 @@ class SyncTestCase(tests.unittest.HomeserverTestCase):
         )
         self.assertEquals(e.value.errcode, Codes.RESOURCE_LIMIT_EXCEEDED)
 
-    def _generate_sync_config(self, user_id):
-        return SyncConfig(
-            user=UserID(user_id.split(":")[0][1:], user_id.split(":")[1]),
-            filter_collection=DEFAULT_FILTER_COLLECTION,
-            is_guest=False,
-            request_key="request_key",
-            device_id="device_id",
-        )
+
+def generate_sync_config(user_id: str) -> SyncConfig:
+    return SyncConfig(
+        user=UserID(user_id.split(":")[0][1:], user_id.split(":")[1]),
+        filter_collection=DEFAULT_FILTER_COLLECTION,
+        is_guest=False,
+        request_key="request_key",
+        device_id="device_id",
+    )