[AC-1904] Implement endpoint to retrieve Provider subscription (#3921)

* Refactor Core.Billing prior to adding new logic

* Add ProviderBillingQueries.GetSubscriptionData

* Add ProviderBillingController.GetSubscriptionAsync

test/Api.Test/AdminConsole/Controllers/OrganizationsControllerTests.cs

@@ -56,7 +56,7 @@ public class OrganizationsControllerTests : IDisposable
     private readonly IAddSecretsManagerSubscriptionCommand _addSecretsManagerSubscriptionCommand;
     private readonly IPushNotificationService _pushNotificationService;
     private readonly ICancelSubscriptionCommand _cancelSubscriptionCommand;
-    private readonly IGetSubscriptionQuery _getSubscriptionQuery;
+    private readonly ISubscriberQueries _subscriberQueries;
     private readonly IReferenceEventService _referenceEventService;
     private readonly IOrganizationEnableCollectionEnhancementsCommand _organizationEnableCollectionEnhancementsCommand;
 
@@ -86,7 +86,7 @@ public class OrganizationsControllerTests : IDisposable
         _addSecretsManagerSubscriptionCommand = Substitute.For<IAddSecretsManagerSubscriptionCommand>();
         _pushNotificationService = Substitute.For<IPushNotificationService>();
         _cancelSubscriptionCommand = Substitute.For<ICancelSubscriptionCommand>();
-        _getSubscriptionQuery = Substitute.For<IGetSubscriptionQuery>();
+        _subscriberQueries = Substitute.For<ISubscriberQueries>();
         _referenceEventService = Substitute.For<IReferenceEventService>();
         _organizationEnableCollectionEnhancementsCommand = Substitute.For<IOrganizationEnableCollectionEnhancementsCommand>();
 
@@ -113,7 +113,7 @@ public class OrganizationsControllerTests : IDisposable
             _addSecretsManagerSubscriptionCommand,
             _pushNotificationService,
             _cancelSubscriptionCommand,
-            _getSubscriptionQuery,
+            _subscriberQueries,
             _referenceEventService,
             _organizationEnableCollectionEnhancementsCommand);
     }