fix: 引入Settings的Module

Settings/aconfig/settings_onboarding_experience_flag_declarations.aconfig

@@ -0,0 +1,9 @@
+package: "com.android.settings.flags"
+container: "system"
+
+flag {
+  name: "enable_sound_backup"
+  namespace: "onboarding_experience"
+  description: "Feature flag for B&R sound settings."
+  bug: "278975761"
+}