Improve a11y ordering

We use ids to break ties when sorting views just to
guarantee that we won't break sorting. But we don't
want to have our swipe order determined by arbitrary
ids.

Before resorting to such a crude tie-breaker, look at
a view's children to try to break a tie using their
bounds. That sort is more based on what's on the
screen, and will also produce the same result from
the same ui.

Bug: 78348191
Test: Switch access order is much more sensible on
Recents. Also ran a11y cts.

Change-Id: I918eae3b0d27e889a53d05a6ebe925e38ce5d7b4