[MM-35625] Add controller for changing cloud subscription (#17676)

* Add a controller for changing subscription

* Changes for PR

* Another change

* Fix pipeline

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

einterfaces/cloud.go

@@ -20,4 +20,6 @@ type CloudInterface interface {
 	GetSubscription(userID string) (*model.Subscription, error)
 	GetInvoicesForSubscription(userID string) ([]*model.Invoice, error)
 	GetInvoicePDF(userID, invoiceID string) ([]byte, string, error)
+
+	ChangeSubscription(userID, subscriptionID string, subscriptionChange *model.SubscriptionChange) (*model.Subscription, error)
 }