[PM-212] Sync Organization Billing Email from Stripe Webhook (#3305)

* Add StripeFacade and StripeEventService

* Add StripeEventServiceTests

* Handle customer.updated event in StripeController

test/Billing.Test/Utilities/StripeTestEvents.cs

@@ -0,0 +1,33 @@
+using Stripe;
+
+namespace Bit.Billing.Test.Utilities;
+
+public enum StripeEventType
+{
+    ChargeSucceeded,
+    CustomerSubscriptionUpdated,
+    CustomerUpdated,
+    InvoiceCreated,
+    InvoiceUpcoming,
+    PaymentMethodAttached
+}
+
+public static class StripeTestEvents
+{
+    public static async Task<Event> GetAsync(StripeEventType eventType)
+    {
+        var fileName = eventType switch
+        {
+            StripeEventType.ChargeSucceeded => "charge.succeeded.json",
+            StripeEventType.CustomerSubscriptionUpdated => "customer.subscription.updated.json",
+            StripeEventType.CustomerUpdated => "customer.updated.json",
+            StripeEventType.InvoiceCreated => "invoice.created.json",
+            StripeEventType.InvoiceUpcoming => "invoice.upcoming.json",
+            StripeEventType.PaymentMethodAttached => "payment_method.attached.json"
+        };
+
+        var resource = await EmbeddedResourceReader.ReadAsync("Events", fileName);
+
+        return EventUtility.ParseEvent(resource);
+    }
+}