Function create_room_handler 

async fn create_room_handler(
    __arg0: State<ServerState>,
    __arg1: AuthenticatedClientRequest<Request>,
) -> Result<ArminiusResponse<Response>, ErrorOf<CreateRoom>>

Handler for POST /_matrix/client/v3/createRoom (See https://spec.matrix.org/latest/client-server-api/#post_matrixclientv3createroom).

This endpoint is used to create a room.