private async void btnAddStepColumns_Click(object sender, EventArgs e)
 {
     try
     {
         var step = (dgvSteps.DataSource as BindingSource).Current as DataMigration.Step;
         await _migrator.AddStepColumnsAsync(_doc.Document, step);
     }
     catch (Exception exc)
     {
         MessageBox.Show(exc.Message);
     }
 }