private void ButtonChangeState_Click(object sender, EventArgs e)
        {
            FormExistCustomer formExistCustomer = new FormExistCustomer(r_GarageManager);

            formExistCustomer.ShowDialog();
            if (formExistCustomer.DialogResult == DialogResult.OK)
            {
                FormVehicleStates formVehicleStates = new FormVehicleStates("Change", formExistCustomer.CustomerToTreat, r_GarageManager);
                formVehicleStates.ShowDialog();
            }
        }
        private void ButtonShowAllVehicles_Click(object sender, EventArgs e)
        {
            FormVehicleStates formVehicleStates = new FormVehicleStates("Show", r_GarageManager);

            formVehicleStates.ShowDialog();
        }