Enhance positionToolbarAlertBanner for grouping

[nimo23]

Currently, the positionToolbarAlertBanner can be set to head-overlay. I don't understand what this means, since it exhibits the same behavior if set to none. The property is also undocumented (see https://www.material-react-table.com/docs/guides/aggregation#relevant-table-options).

It would be nice to use the head-overlay property or another new property to reuse the (first) column header (= the header that indicates the grouping order) as clickable elements. Then, when I click on an element (e.g., age), the age grouping is removed. The advantage is that we don't need duplicate grouping information (above the columns and in the column header) and save space (important on smaller devices).

The clickable chips can then be further customized by the user using dedicated muiXProps.