Add recent apps in app & notification

- Introduce a RecentAppsPreferenceControler, which queries
  UsageStatsManager and displays a list of recently used apps.

- Add a control flag for this feature, intially set to false.

- Make ManageApplications a static pref item instead of dynamic one.
  This makes the RecentAppController easier to control "See all"
  preference, which is backed by ManageApplications.

- Also adjust app_items.xml layout to make app item UI consistent with
  preference item.

Change-Id: I0b9e1784faed32b3055ebf96ef98b6a5e422de50
Fix: 33265548
Test: robotests

res/xml/app_and_notification.xml

@@ -20,6 +20,27 @@
     xmlns:settings="http://schemas.android.com/apk/res/com.android.settings"
     android:title="@string/app_and_notification_dashboard_title">
 
+    <PreferenceCategory
+        android:key="recent_apps_category"
+        android:title="@string/recent_app_category_title"
+        android:order="-200">
+        <!-- Placeholder for a list of recent apps -->
+
+        <!-- See all apps button -->
+        <Preference
+            android:title="@string/applications_settings"
+            android:key="all_app_info"
+            android:summary="@string/summary_placeholder"
+            android:order="20">
+            <intent
+                android:action="android.intent.action.MAIN"
+                android:targetPackage="com.android.settings"
+                android:targetClass="com.android.settings.Settings$ManageApplicationsActivity">
+                <extra android:name="show_drawer_menu" android:value="true" />
+            </intent>
+        </Preference>
+    </PreferenceCategory>
+
     <Preference
         android:key="manage_perms"
         android:title="@string/app_permissions"