Expose get/set notification listeners as a @SystemAPI

We need to grant/revoke notification listener privileges from
PermissionController maniline module.
This exposes a @SystemApi API to do so

Bug: 165951651
Test: atest NotificationManagerTest
Change-Id: I81502756e9c7f11ce0347f5f3c006a1539f91b37
diff --git a/packages/Shell/AndroidManifest.xml b/packages/Shell/AndroidManifest.xml
index bba29db..5f018a0 100644
--- a/packages/Shell/AndroidManifest.xml
+++ b/packages/Shell/AndroidManifest.xml
@@ -335,6 +335,9 @@
     <!-- Permission required for CTS test - android.server.biometrics -->
     <uses-permission android:name="android.permission.TEST_BIOMETRIC" />
 
+    <!-- Permissions required for CTS test - NotificationManagerTest -->
+    <uses-permission android:name="android.permission.MANAGE_NOTIFICATION_LISTENERS" />
+
     <application android:label="@string/app_label"
                 android:theme="@android:style/Theme.DeviceDefault.DayNight"
                 android:defaultToDeviceProtectedStorage="true"