Add option to set related groups for created rooms

mautrix_telegram/config.py

@@ -189,6 +189,8 @@ class Config(DictWithRecursion):
         copy("appservice.bot_displayname")
         copy("appservice.bot_avatar")
 
+        copy("appservice.community_id")
+
         copy("appservice.as_token")
         copy("appservice.hs_token")
 
@@ -352,3 +354,6 @@ class Config(DictWithRecursion):
             "sender_localpart": self["appservice.bot_username"],
             "rate_limited": False
         }
+        if self["appservice.community_id"]:
+            self._registration["namespaces"]["users"][0]["group_id"] \
+                = self["appservice.community_id"]

mautrix_telegram/portal.py

@@ -397,6 +397,11 @@ class Portal:
             "type": "m.room.power_levels",
             "content": power_levels,
         }]
+        if config["appservice.community_id"]:
+            initial_state.append({
+                "type": "m.room.related_groups",
+                "content": {"groups": [config["appservice.community_id"]]},
+            })
 
         room_id = await self.main_intent.create_room(alias=alias, is_public=public,
                                                      is_direct=direct, invitees=invites or [],