Create settings screen for Notification Assistant

Test: this atest
Test: manual: change assistant and "adb shell dumpsys notification"
Test: manual: verify persistance through reboot (including none)

Fixes:120852765
Change-Id: Ie4516c3339246d66d7b6719ac5dd1d65c4d03b57
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index a94801f..fb6dad6 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -2335,6 +2335,18 @@
         </activity>
 
         <activity
+            android:name="Settings$NotificationAssistantSettingsActivity"
+            android:label="@string/notification_assistant_title"
+            android:parentActivityName="Settings">
+            <intent-filter android:priority="1">
+                <action android:name="android.settings.NOTIFICATION_ASSISTANT_SETTINGS" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+            <meta-data android:name="com.android.settings.FRAGMENT_CLASS"
+                       android:value="com.android.settings.notification.NotificationAssistantPicker" />
+        </activity>
+
+        <activity
             android:name="Settings$VrListenersSettingsActivity"
             android:label="@string/vr_listeners_title"
             android:parentActivityName="Settings">