Add debug page in gallery to show page & entry debug information.

Bug: 244122804
Test: manual - build Spa gallery
Change-Id: I4853e17028dfe0eed4342b4691962b508bc87357
diff --git a/packages/SettingsLib/Spa/gallery/AndroidManifest.xml b/packages/SettingsLib/Spa/gallery/AndroidManifest.xml
index 2229986..e5bf8ca 100644
--- a/packages/SettingsLib/Spa/gallery/AndroidManifest.xml
+++ b/packages/SettingsLib/Spa/gallery/AndroidManifest.xml
@@ -29,6 +29,10 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-    </application>
 
+        <activity
+            android:name=".GalleryDebugActivity"
+            android:exported="true">
+        </activity>
+    </application>
 </manifest>