Build a new FooterPreference UI.

- Create a new layout for footer prefs.
- Create a new FooterPreference type to use the layout
- Create a Mixin to create and add the pref to screen
- Create a new lifecycle observer type to invoke mixin at right time
- Switch SettingsPreferenceFragment to use footer mixin.
- Switch FingerprintSettings to use the new footer pref.

Bug: 33579394
Test: RunSettingsRoboTests
Change-Id: I548ac39a0d120196a7ffed09b4f98bd9a80bae90

src/com/android/settings/applications/ApplicationFeatureProvider.java

@@ -35,7 +35,7 @@ public interface ApplicationFeatureProvider {
     /**
      * Callback that receives the total number of packages installed on the device.
      */
-    public interface NumberOfInstalledAppsCallback {
+    interface NumberOfInstalledAppsCallback {
         void onNumberOfInstalledAppsResult(int num);
     }
 }