As part of ##55632, we identified that we need to have the container of the split view primerized

* Tab row Begin of the insertionusing `UnderlineNav`End of the insertion

* Begin of the insertionContent of the tabs will stay as is

* End of the insertion Possibly the "toolbar" / action buttons at the bottom Begin of the insertionat a later stageEnd of the insertion Begin of the deletion

* Content of the tabs will stay as isEnd of the deletion