Implement swipe gesture for staged split in landscape

* Maintain task split percentages when swiping up.
* Split percentages not maintained in GroupedTaskView, however.
That is a TODO.

Bug: 181704764, 181705607
Test: Swiped up in landscape with home rotation on/off.
Portrait still works.

Change-Id: Iec62abae34f6ccadf98e2afdc9409cf3160f8223