Sets views clickable according to their visibility

Captures clicks on QuickStatusBarHeader so they don't go through and
collapse QS (broken in ag/4773943). This includes the black status bar
(therefore, it's independent of expansion).

Small targets in QSFooterImpl that were obscured were registering
clicks, as QSFooterImpl is VISIBLE even if its elements are not.

Test: Manual
Change-Id: Ie36096355c8a0e8417194ef0f123d5e7b95a7e95
Fixes: 120873445
Fixes: 120677657