Allow gems and subs to be gifted through in-app-purchases (#10892)

* Allow gems to be gifted through IAPs

* implement non recurring IAP subscriptions

* fix localization issue in error

* fix non renewing subscription handling

* Fix lint error

* fix tests

* move findbyId mock to helper file

* undo package-lock changes

* Fix lint error

test/helpers/mongoose.helper.js

@@ -0,0 +1,20 @@
+import mongoose from 'mongoose';
+
+export async function mockFindById (response) {
+  const mockFind = {
+    select () {
+      return this;
+    },
+    lean () {
+      return this;
+    },
+    exec () {
+      return Promise.resolve(response);
+    },
+  };
+  sinon.stub(mongoose.Model, 'findById').returns(mockFind);
+}
+
+export function restoreFindById () {
+  return mongoose.Model.findById.restore();
+}