fdo#81617: Write test for this first.

This test currently crashes.

Change-Id: I57133495b483664c960a15e638520d195eb02070
fdo#81617: Split formula groups at sort range boundaries.

Otherwise, partially sorting a range may crash, or at best incorrectly
update formula references.

Change-Id: Iefcb86d205d83ccc5b684048bfd9aadabf6e13eb