[MM-28217] Server API to serve up cloud customer information (#15656)

* [MM-28217] Server API to serve up cloud customer information

* Added missing client4 method

* merge'd

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

einterfaces/cloud.go

@@ -13,5 +13,7 @@ type CloudInterface interface {
 	CreateCustomerPayment() (*model.StripeSetupIntent, *model.AppError)
 	ConfirmCustomerPayment(*model.ConfirmPaymentMethodRequest) *model.AppError
 
+	GetCloudCustomer() (*model.CloudCustomer, *model.AppError)
+
 	GetSubscription() (*model.Subscription, *model.AppError)
 }