Fix undo redo of textranges - we might have swapped anchor and pos

in general that would not be that big a deal if not for a qt bug which makes the anchor travel even if
the qtextcursor has keepPositionOnInsert() == true

There was another part to this bug - we didn't make sure the text was relayouted

so in short: the anchor was lost (misplaced) and the relayout was never initiated

BUG: 342869