Add Global Settings to device whether show Carrier menu

Add Global Settings EUICC_SUPPORTED_COUNTRIES. When the device enabled
esim UI by default and the users in eSIM supported countries, even if
eSIM is not provisioned, carrier menu will be shown. This global
settings will be updated by eSIM mamanger when the phone boot up.

Bug: 77638033
Test: E2E
Change-Id: Ib3ac8bcdfab56d6cd7c12e48318f1794af5bc1aa
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 5b7adf0..efec471 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -8744,6 +8744,17 @@
         public static final String EUICC_PROVISIONED = "euicc_provisioned";
 
         /**
+         * List of ISO country codes in which eUICC UI is shown. Country codes should be separated
+         * by comma.
+         *
+         * <p>Used to hide eUICC UI from users who are currently in countries no carriers support
+         * eUICC.
+         * @hide
+         */
+        //TODO(b/77914569) Changes this to System Api.
+        public static final String EUICC_SUPPORTED_COUNTRIES = "euicc_supported_countries";
+
+        /**
          * Whether any activity can be resized. When this is true, any
          * activity, regardless of manifest values, can be resized for multi-window.
          * (0 = false, 1 = true)
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index 558e576..196f8de 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -228,6 +228,7 @@
                     Settings.Global.EPHEMERAL_COOKIE_MAX_SIZE_BYTES,
                     Settings.Global.ERROR_LOGCAT_PREFIX,
                     Settings.Global.EUICC_PROVISIONED,
+                    Settings.Global.EUICC_SUPPORTED_COUNTRIES,
                     Settings.Global.EUICC_FACTORY_RESET_TIMEOUT_MILLIS,
                     Settings.Global.FANCY_IME_ANIMATIONS,
                     Settings.Global.FORCE_ALLOW_ON_EXTERNAL,