Draw a default focus highlight if needed.

This commit draws a default highlight for a focused
View if it's detected to have no state_focused defined
and its useDefaultFocusHighlight attribute is true.

When we detect a default highlight is needed, we show it
on top of the view to. Once we detect that it's no longer
needed, we remove it.

Test: Check that views without a focused_state in its
state spec have a default highlight when they get focused.
Bug: 35096940

Change-Id: Ifbe4bb9e1297d98845314e24d8b758f14e5987a9