Add a rust library for android.security flags

Make it possible for rust code such as keystore2 to check
android.security flags.

Bug: 296464083
Test: Tested accessing flag from keystore2
Change-Id: I52c6803ab712c76573a1ac70eb7734eb5f7f8f73

AconfigFlags.bp

@@ -147,6 +147,12 @@ java_aconfig_library {
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
 
+rust_aconfig_library {
+    name: "libandroid_security_flags_rust",
+    crate_name: "android_security_flags",
+    aconfig_declarations: "android.security.flags-aconfig",
+}
+
 // Package Manager
 aconfig_declarations {
     name: "android.content.pm.flags-aconfig",