Added stripe customer fetching method to member's API

no issue

- This method is needed to be able to validate if customer exist in configured Stripe account before attempting to link one with local member.

ghost/members-api/lib/stripe/index.js

@@ -153,6 +153,10 @@ module.exports = class StripePaymentProcessor {
         return customer;
     }
 
+    async getStripeCustomer(id) {
+        return await retrieve(this._stripe, 'customers', id);
+    }
+
     async createCheckoutSetupSession(member, options) {
         const customer = await this._customerForMemberCheckoutSession(member);
 

ghost/members-api/lib/users.js

@@ -89,6 +89,12 @@ module.exports = function ({
         }
     }
 
+    async function getStripeCustomer(id) {
+        if (stripe) {
+            return await stripe.getStripeCustomer(id);
+        }
+    }
+
     async function get(data, options) {
         debug(`get id:${data.id} email:${data.email}`);
         const member = await getMember(data, options);
@@ -189,6 +195,7 @@ module.exports = function ({
         setComplimentarySubscription,
         cancelComplimentarySubscription,
         destroyStripeSubscriptions,
+        getStripeCustomer,
         linkStripeCustomer
     };
 };