Check visibility when moving task to front.

Currently when we move a task to the front, we try to resume its
top-most activity and pause the back stacks. However, in a multi-resume
world, it's possible that this becomes a resume -> resume operation,
which no-ops and exits early without pausing the back stack. Instead, we
should check visibility before trying to resume the activity, in order
to update any other tasks that are now no longer visible and thus should
be STOPPED or PAUSED.

Bug: 168852384
Test: atest
PinnedStackTests#testAutoEnterPictureInPictureOnUserLeaveHintWhenPipRequestedNotOverridden

Change-Id: I4dfdaab1f2b0c2116121e460cf3e3183107662e2