The `onConnect` and `setNotificationHandler` callback should provide the `ServerSession`

[ghostflyby]

Is your feature request related to a problem? Please describe.
I've been trying to create a reactive listener based on per-session roots notification and found it impossible or wired.

onConnect {
    sessions.forEach { (_, session) ->
        session.setNotificationHandler<RootsListChangedNotification>(Method.Defined.NotificationsRootsListChanged) {
            scope.launch {
                session.listRoots()

                // do Something with roots per session
            }
            CompletableDeferred()
        }
    }
}

I have to reset notifications for all sessions on each new session to properly get the per-session info.

Describe the solution you'd like

onConnect { session : ServerSession -> 
// do something with session
}

or

server.setNotificationHandler<RootsListChangedNotification>(Method.Defined.NotificationsRootsListChanged) {session : ServerSession -> 
// do something with session
}

or both.

Other infos

I suspect that the no-session-arg style onConnect and other callbacks are the legacy of the old new server per transport architecture.