Add day-night-mode permission to Shell.

Without the permission "adb shell cmd uimode night <mode>" doesn't work.
Adding the permission to the AndroidManifest file so the shell command
will work.

Bug: 155584597
Test: run `adb shell cmd uimode night <no|yes|auto>`
Change-Id: Ibfb145d762c73bba9de639d4050b9b26e4778cc9
diff --git a/packages/Shell/AndroidManifest.xml b/packages/Shell/AndroidManifest.xml
index ff91c79..d34291d 100644
--- a/packages/Shell/AndroidManifest.xml
+++ b/packages/Shell/AndroidManifest.xml
@@ -219,6 +219,9 @@
     <uses-permission android:name="android.permission.READ_COMPAT_CHANGE_CONFIG"/>
     <uses-permission android:name="android.permission.OVERRIDE_COMPAT_CHANGE_CONFIG"/>
 
+    <!-- Permission required for CTS test - BatterySaverTest -->
+    <uses-permission android:name="android.permission.MODIFY_DAY_NIGHT_MODE"/>
+
     <!-- Permission required for CTS test - UiModeManagerTest -->
     <uses-permission android:name="android.permission.ENTER_CAR_MODE_PRIORITIZED"/>