Add feature flag to define system API for IMS service.

This commit adds a feature flag to define system API for IMS service.
These flags allow use of specific APIs as system API.

Bug: 365488868
Test: build pass
Flag: com.android.internal.telephony.flags.support_ims_mmtel_interface
Flag: com.android.internal.telephony.flags.support_isim_record
Change-Id: Idf3d847fcdf2348a09befa9e30fd4cbffad6e282
diff --git a/flags/uicc.aconfig b/flags/uicc.aconfig
index ad0c59f..abe4296 100644
--- a/flags/uicc.aconfig
+++ b/flags/uicc.aconfig
@@ -79,4 +79,12 @@
     metadata {
         purpose: PURPOSE_BUGFIX
     }
-}
\ No newline at end of file
+}
+
+# OWNER=jhyoon TARGET=25Q2
+flag {
+    name: "support_isim_record"
+    namespace: "telephony"
+    description: "This flag controls the type of API that retrieves ISIM records, either hidden or system type."
+    bug:"359721349"
+}