SystemUI: add a disabled state for Quick Tiles

Some tiles may want to be visible, but not allow any user interaction
due to security reasons. Add a visual disabled state for tiles which are
not enabled.

With this patch, the Profiles tile and the Lockscreen toggle tile
disable themselves on a secure lock screen.

Change-Id: I65ec7837661483d238d8dc3fa18419f76c8029dd
Signed-off-by: Roman Birg <roman@cyngn.com>