message: Use connector registry to fetch the table column class.
diff: @@ -1792,7 +1792,9 @@ class Superset(BaseSupersetView):
  metrics = []
  for column_name, config in data.get('columns').items():
  is_dim = config.get('is_dim', False)
  - col = models.TableColumn(
  + SqlaTable = ConnectorRegistry.sources['table']
  + TableColumn = SqlaTable.column_cls
  + col = TableColumn(
  column_name=column_name,
  filterable=is_dim,
  groupby=is_dim,
  