Federated typing indicators with same userId

Since it's not directly related to federated calls, I thought creating a new issue makes the most sense.

While testing https://github.com/nextcloud/spreed/pull/12604 I was unable to get typing indicators to work at first. For my testing I used the same userId on both servers, so I basically had 2 admins in my conversation:

Since we suppress typing indicators for ourselves, the federated indicator did not show up, but the signaling messages from that user were received fine.

Purely from the signaling message, I don't see a way to distinguish if it's "my" userId or a federated one:

{
  "type": "message",
  "message": {
    "sender": {
      "type": "session",
      "sessionid": "Tco...",
      "userid": "admin"
    },
    "data": {
      "type": "startedTyping",
      "to": "2fJ7u..."
    }
  }
}

Review pull request 12604 and the signaling handling for startedTyping messages, then reproduce the case with the same userId on both servers. Trace where typing indicators are suppressed for the local user and define a way for the federated indicator to remain visible; done means the indicator works in this setup without breaking local-user suppression.