Setting Room Successors

### Your use case

#### What would you like to do?
Let room admins set a room successor.

#### Why would you like to do it?
Reduce unmoderated rooms.
Hedge against settings mismanagement.
Hedge against account/server shutdown.

#### How would you like to achieve it?
An on/off toggle: "Room Successor".
A few parameters/triggers e.g. Admin left or Left for *X time* etc.
A field for proposed successors.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you able to provide a PR?

No