AOD: Add temporary always-on setting

Adds a setting for controlling always-on ambient display
until the new ambient display settings screen is implemented.

Also updates DozePreferenceController to use the the
AmbientDisplayConfiguration helper instead of recreating that
logic.

Also adds tests for both doze preference controllers.

Bug: 33279975
Test: Toggle "Settings > Display > Always on", verify ambient display is on / off
Test: make RunSettingsRoboTests
Change-Id: If36356bc29329a4e0732e79db662ffb02c9fc189

tests/robotests/src/com/android/internal/hardware/AmbientDisplayConfiguration.java

@@ -16,7 +16,6 @@
 
 package com.android.internal.hardware;
 
-import android.provider.Settings;
 import android.content.Context;
 
 /**
@@ -42,4 +41,20 @@ public class AmbientDisplayConfiguration {
     public boolean pulseOnDoubleTapEnabled(int user) {
         return true;
     }
+
+    public boolean pulseOnNotificationEnabled(int user) {
+        return true;
+    }
+
+    public boolean pulseOnNotificationAvailable() {
+        return true;
+    }
+
+    public boolean alwaysOnEnabled(int user) {
+        return true;
+    }
+
+    public boolean alwaysOnAvailable() {
+        return true;
+    }
 }