[Call Screening]Default call screening app setting storage.

Add new string in Settings. To indicate which app is default
call screening, similar to default dialer application setting,
store this in the system settings provider.

Bug: 118416082
Test: atest SettingsBackupTest pass.
Change-Id: I39f81b31a68ee2dbb056ff935f8dea0f51720017

core/java/android/provider/Settings.java

@@ -7298,6 +7298,14 @@ public final class Settings {
         @UnsupportedAppUsage
         public static final String DIALER_DEFAULT_APPLICATION = "dialer_default_application";
 
+        /**
+         * Specifies the component name currently configured to be the default call screening
+         * application
+         * @hide
+         */
+        public static final String CALL_SCREENING_DEFAULT_COMPONENT =
+                "call_screening_default_component";
+
         /**
          * Specifies the package name currently configured to be the default application to perform
          * the user-defined call redirection service with Telecom.

core/tests/coretests/src/android/provider/SettingsBackupTest.java

@@ -530,6 +530,7 @@ public class SettingsBackupTest {
                  Settings.Secure.BACKUP_PROVISIONED,
                  Settings.Secure.BACKUP_TRANSPORT,
                  Settings.Secure.CALL_REDIRECTION_DEFAULT_APPLICATION,
+                 Settings.Secure.CALL_SCREENING_DEFAULT_COMPONENT,
                  Settings.Secure.CAMERA_LIFT_TRIGGER_ENABLED, // Candidate for backup?
                  Settings.Secure.CARRIER_APPS_HANDLED,
                  Settings.Secure.CMAS_ADDITIONAL_BROADCAST_PKG,