Adjust QS side spacing in split shade according to specs

QS should have 40dp margins on both sides.
Dimensions in QS were dependent on dimensions of notification so I extracted them to separate dimensions - dependendent on notifications in regular shade but indepedent in large screen shade.
Also created new qs_tiles_page_horizontal_margin because it should have different value on its own for large screen, otherwise clipping of QS tiles while swiping was not reaching edge of screen and notification scrim.

Fixes: 228056456
Test: open split shade QS and swipe between tile pages
Change-Id: Ie72548b6a84aaf43381b5da497aa7912a0eb7b1d