isSubscriptionAssociatedWithUser Implementation

Implements a public API in which a caller can determine whether the
given subscription is associated with their own user.

Bug: 325045841
Test: atest SubscriptionManagerTest -c
Change-Id: Ib09527a497a7108dca3777c4ee310f8a551baf22
diff --git a/flags/subscription.aconfig b/flags/subscription.aconfig
index fa77fc3..cebedd5 100644
--- a/flags/subscription.aconfig
+++ b/flags/subscription.aconfig
@@ -33,4 +33,11 @@
   namespace: "telephony"
   description: "Support the psim to esim conversion."
   bug: "315073761"
+}
+
+flag {
+  name: "subscription_user_association_query"
+  namespace: "telephony"
+  description: "Supports querying if a subscription is associated with the caller"
+  bug: "325045841"
 }
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