SystemUI: add Settings.System toggle for quick-quick settings pulldown

Change-Id: I3c5dcfc23f39bf8be6c402e25f61e6f57a8add2c
Signed-off-by: Roman Birg <roman@cyngn.com>

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
SystemUI: PhoneStatusBarView: disable DEBUG_GESTURES

Change-Id: I3911c464d1f008ac2c96a1104761007fad41a3ae
Signed-off-by: Roman Birg <roman@cyngn.com>
SystemUI: Add double tap to sleep

* Make it more reliable
* Add it to keyguard
* Add a content observer to not always query Settings.System on every
touch event

Change-Id: I292c4d9d9f810843590b7a9ec6e15b99ac44009d
Signed-off-by: Roman Birg <roman@cyngn.com>