[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>

model/cloud.go

@@ -156,3 +156,7 @@ type SubscriptionStats struct {
 	IsPaidTier     string `json:"is_paid_tier"`
 	IsFreeTrial    string `json:"is_free_trial"`
 }
+
+type SubscriptionChange struct {
+	ProductID string `json:"product_id"`
+}