Create exported mode flag library for package android.os

This change creates exported mode flag library for package android.os.
This exported flag library should be used in other containers.

Bug: 321743530
Test: presubmit
Change-Id: Idd1323ac8ac17833df1a7de6642262384f253095

AconfigFlags.bp

@@ -310,6 +310,8 @@ java_aconfig_library {
 aconfig_declarations {
     name: "android.os.flags-aconfig",
     package: "android.os",
+    exportable: true,
+    container: "system",
     srcs: ["core/java/android/os/*.aconfig"],
 }
 
@@ -326,6 +328,13 @@ java_aconfig_library {
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
 
+java_aconfig_library {
+    name: "android.os.flags-aconfig-java-export",
+    aconfig_declarations: "android.os.flags-aconfig",
+    defaults: ["framework-minus-apex-aconfig-java-defaults"],
+    mode: "exported",
+}
+
 // VirtualDeviceManager
 cc_aconfig_library {
     name: "android.companion.virtualdevice.flags-aconfig-cc",

core/java/android/os/flags.aconfig

 package: "android.os"
+container: "system"
 
 flag {
     name: "android_os_build_vanilla_ice_cream"
@@ -40,6 +41,7 @@ flag {
     namespace: "profile_experiences"
     description: "Guards a new Private Profile type in UserManager - everything from its setup to config to deletion."
     bug: "299069460"
+    is_exported: true
 }
 
 flag {