Function joined_rooms_handler 

async fn joined_rooms_handler(
    __arg0: State<ServerState>,
    __arg1: AuthenticatedClientRequest<Request>,
) -> Result<ArminiusResponse<Response>, InternalServerError>

Handler for GET /_matrix/client/v3/joined_rooms (See https://spec.matrix.org/v1.18/client-server-api/#get_matrixclientv3joined_rooms).

This endpoint returns the list of rooms that the user is a member of