Create ResourceBasedOverride for SearchSessionManager.

This override will allow Launcher3 to initialize and control a search session implementation.

Bug: 216683257
Test: Manual
Change-Id: I43d4793ef176cfd8e074961286356b96f9222ca9
diff --git a/res/values/config.xml b/res/values/config.xml
index e2fd0e3..76d1161 100644
--- a/res/values/config.xml
+++ b/res/values/config.xml
@@ -91,6 +91,7 @@
     <string name="custom_activity_picker" translatable="false">
         com.android.customization.picker.CustomizationPickerActivity</string>
     <string name="local_colors_extraction_class" translatable="false"></string>
+    <string name="search_session_manager_class" translatable="false"></string>
 
     <!-- Accessibility actions -->
     <item type="id" name="action_remove" />