Long-press to configure quick affordances (1/2).

Adds logic to allow quick affordance configuration through a long-press
in the wallpaper picker UI. Also adds such a configuration long-press
for the Do Not Disturbe (DND) affordance.

Fix: 261747112
Test: unit test added
Test: manually verified that long-press on the DND quick affordance
opens the DND settings activity
Test: manually verified that select/unselect all still work

Change-Id: Iabc67f62a106f5d48d6a0dab32096a27d1ff5fed