Navigation Bar: Toggle last app on recents button long press

Long pressing the recent apps button on the navigation bar will launch the last open app.
Cherry-picked from https://github.com/omnirom/android_frameworks_base/commit/6fb093b3311942beae7f51e23abbf18aa8c99bf8

Change-Id: I1e6d6255494991b440f3cf5854a7edad7fee2c1b

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
PS2: Removed unwanted imports and tabs.

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
Add clear all recents button to in-the-spot user preference

Change-Id: I53c7d5f881542d2644aac8cc09e49ae1c5543bcb

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/values-es/pa_strings.xml
	packages/SystemUI/res/values/pa_strings.xml