add invited count, only copy summary fields if present in summary

only copy any member from summary as
they are only in the response when they change.
Also accumulate them in the sync accumulator

src/sync.js

@@ -823,7 +823,11 @@ SyncApi.prototype._processSyncResponse = async function(
     //          state: { events: [] },
     //          timeline: { events: [], prev_batch: $token, limited: true },
     //          ephemeral: { events: [] },
-    //          summary: { m.heroes: [ $userId ], m.joined_member_count: $count }
+    //          summary: {
+    //             m.heroes: [ $user_id ],
+    //             m.joined_member_count: $count,
+    //             m.invited_member_count: $count
+    //          },
     //          account_data: { events: [] },
     //          unread_notifications: {
     //              highlight_count: 0,