Fix Storybook compilation warning

Typescript import and export has to be explicit.
Related issue #700
Related PR #701

packages/core/src/components/Table/index.ts

@@ -14,5 +14,6 @@
  * limitations under the License.
  */
 
-export { default, TableColumn } from './Table';
+export { default } from './Table';
+export type { TableColumn } from './Table';
 export { default as SubvalueCell } from './SubvalueCell';