Group Lifetime Events in signalr

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

Signalr clients have lifetime events like `OnConnectedAsync` and `OnDisconnectedAsync`. But the groups don't have events like `OnCreate`, `OnRemove`, `OnUserAdd`, `OnUserRemove` etc.

Before Signal I used to use socket.io(nodejs library) which has rooms similar to signalr groups. But I can find more features in rooms of socket.io than signalr's groups.

### Describe the solution you'd like

Group events will be good to have if it is possible to implement.

### Additional context

_No response_