Send a broadcast for grayscale changed

Add android.settings.action.GRAYSCALE_CHANGED to protected broadcast
list.

Bug: 118387886
Test: manual
Change-Id: I67c49ead44c81880bceef708315ed98c8a69508a
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index fb92fbf..de526ef 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -618,6 +618,7 @@
 
     <!-- Added in Q -->
     <protected-broadcast android:name="android.content.pm.action.SESSION_UPDATED" />
+    <protected-broadcast android:name="android.settings.action.GRAYSCALE_CHANGED" />
 
     <!-- For CarIdlenessTracker -->
     <protected-broadcast android:name="com.android.server.jobscheduler.GARAGE_MODE_ON" />