[PM-21383] Use Stripe to get provider pricing for display when feature flag is on (#5842)

* Use ProviderPriceAdapter when getting provider subscription

* Update test

src/Core/Billing/Models/ConfiguredProviderPlan.cs

@@ -6,6 +6,7 @@ public record ConfiguredProviderPlan(
     Guid Id,
     Guid ProviderId,
     Plan Plan,
+    decimal Price,
     int SeatMinimum,
     int PurchasedSeats,
     int AssignedSeats);

src/Core/Constants.cs

@@ -150,6 +150,7 @@ public static class FeatureFlagKeys
     public const string UseOrganizationWarningsService = "use-organization-warnings-service";
     public const string PM20322_AllowTrialLength0 = "pm-20322-allow-trial-length-0";
     public const string PM21092_SetNonUSBusinessUseToReverseCharge = "pm-21092-set-non-us-business-use-to-reverse-charge";
+    public const string PM21383_GetProviderPriceFromStripe = "pm-21383-get-provider-price-from-stripe";
 
     /* Data Insights and Reporting Team */
     public const string RiskInsightsCriticalApplication = "pm-14466-risk-insights-critical-application";

src/Core/Services/IStripeAdapter.cs

@@ -57,4 +57,5 @@ public interface IStripeAdapter
     Task<SetupIntent> SetupIntentGet(string id, SetupIntentGetOptions options = null);
     Task SetupIntentVerifyMicroDeposit(string id, SetupIntentVerifyMicrodepositsOptions options);
     Task<List<Stripe.TestHelpers.TestClock>> TestClockListAsync();
+    Task<Price> PriceGetAsync(string id, PriceGetOptions options = null);
 }

src/Core/Services/Implementations/StripeAdapter.cs

@@ -283,4 +283,7 @@ public class StripeAdapter : IStripeAdapter
         }
         return items;
     }
+
+    public Task<Price> PriceGetAsync(string id, PriceGetOptions options = null)
+        => _priceService.GetAsync(id, options);
 }