Add NightDisplaySettingsActivity

- The Settings#ACTION_NIGHT_DISPLAY_SETTINGS action can be used by apps
  to launch Night display settings directly.

Bug: 30291948
Change-Id: I5545bb7f0a467116454e5c44e207cbe91ddf9d43
diff --git a/src/com/android/settings/Settings.java b/src/com/android/settings/Settings.java
index 3036bd18..feeabe7 100644
--- a/src/com/android/settings/Settings.java
+++ b/src/com/android/settings/Settings.java
@@ -50,6 +50,7 @@
     public static class UserDictionarySettingsActivity extends SettingsActivity { /* empty */ }
     public static class HomeSettingsActivity extends SettingsActivity { /* empty */ }
     public static class DisplaySettingsActivity extends SettingsActivity { /* empty */ }
+    public static class NightDisplaySettingsActivity extends SettingsActivity { /* empty */ }
     public static class DeviceInfoSettingsActivity extends SettingsActivity { /* empty */ }
     public static class ApplicationSettingsActivity extends SettingsActivity { /* empty */ }
     public static class ManageApplicationsActivity extends SettingsActivity { /* empty */ }