fix(emails): Subscription invoice emails have outdate email addresses

Because:

* When a customer changes their FxA account email, this change is not propagated through to Stripe
* Emails relating to Stripe's invoices pull the customer's email field from their invoice
* This causes these emails to contain outdated email addresses

This commit:

* Because the text of the invoice references the customer receiving the email because there is a Mozilla account with the listed email address, this commit updates the emails to use the account's primary email for these fields.

Closes #PAY-3215

Author: david1alvarez

packages/fxa-auth-server/lib/routes/subscriptions/stripe-webhook.ts

@@ -949,6 +949,7 @@ export class StripeWebhookHandler extends StripeHandler {
       {
         acceptLanguage: account.locale,
         ...invoiceDetails,
+        email: account.primaryEmail
       }
     );
     await this.stripeHelper.updateEmailSent(invoice, 'paymentFailed');
@@ -970,6 +971,7 @@ export class StripeWebhookHandler extends StripeHandler {
       {
         acceptLanguage: account.locale,
         ...invoiceDetails,
+        email: account.primaryEmail
       },
     ];
     switch (invoice.billing_reason) {
@@ -1083,6 +1085,7 @@ export class StripeWebhookHandler extends StripeHandler {
           {
             acceptLanguage: account.locale,
             ...invoiceDetails,
+            email: account.primaryEmail
           }
         );
       } else if (!subscription.cancel_at_period_end) {
@@ -1097,6 +1100,7 @@ export class StripeWebhookHandler extends StripeHandler {
             ...invoiceDetails,
             showOutstandingBalance,
             cancelAtEnd: subscription.cancel_at_period_end,
+            email: account.primaryEmail
           }
         );
       }

packages/fxa-auth-server/test/local/routes/subscriptions/stripe-webhooks.js

@@ -2175,6 +2175,7 @@ describe('StripeWebhookHandler', () => {
         {
           acceptLanguage: mockAccount.locale,
           ...mockInvoiceDetails,
+          email: mockAccount.primaryEmail
         }
       );
     });
@@ -2212,6 +2213,7 @@ describe('StripeWebhookHandler', () => {
           {
             acceptLanguage: mockAccount.locale,
             ...mockInvoiceDetails,
+            email: mockAccount.primaryEmail
           }
         );
         if (expectedMethodName === 'sendSubscriptionFirstInvoiceEmail') {
@@ -2223,6 +2225,7 @@ describe('StripeWebhookHandler', () => {
               {
                 acceptLanguage: mockAccount.locale,
                 ...mockInvoiceDetails,
+                email: mockAccount.primaryEmail
               }
             );
           } else {
@@ -2411,6 +2414,7 @@ describe('StripeWebhookHandler', () => {
             {
               acceptLanguage: mockAccount.locale,
               ...mockInvoiceDetails,
+              email: mockAccount.primaryEmail
             }
           );
         } else {
@@ -2451,6 +2455,7 @@ describe('StripeWebhookHandler', () => {
               ...mockInvoiceDetails,
               showOutstandingBalance: options.hasOutstandingBalance,
               cancelAtEnd: subscription.cancel_at_period_end,
+              email: mockAccount.primaryEmail
             }
           );
         } else {