feat(firestore-stripe-payments): Support payment_method_collection parameter

Author: jsteele-stripe

firestore-stripe-payments/functions/src/index.ts

@@ -145,6 +145,7 @@ exports.createCheckoutSession = functions
       consent_collection = {},
       expires_at,
       phone_number_collection = {},
+      payment_method_collection = 'always'
     } = snap.data();
     try {
       logs.creatingCheckoutSession(context.params.id);
@@ -204,6 +205,7 @@ exports.createCheckoutSession = functions
           sessionCreateParams.payment_method_types = payment_method_types;
         }
         if (mode === 'subscription') {
+          sessionCreateParams.payment_method_collection = payment_method_collection
           sessionCreateParams.subscription_data = {
             trial_from_plan,
             metadata,