Describe the bug
When we use the Native Grid with a sortable configuration set to "{ mode: 'multiple' }" and we have a ColumnMenu, once the sorting functionality of the column menu is used, the sorting is reset.

To Reproduce

1. Open this StackBlitz example
2. Apply sort to the Name and Unit Price columns by clicking on each column header.
   
3. Select the column menu of the Discounted column and click the sort Ascending or Descending button.
   
4. Notice that the previous nested sort applied in the above steps is cleared and only the Discontinued column has an applied sorting.

Expected behavior

The sorting shouldn't be reset no matter which Grid sorting functionality is used. In the above example, the sorting of the Discontinued column should be added to the complex sorting.