MM-43529 - start freemium trial (#20163)

* MM-43529 - start freemium trial

* change the method to put

* Add unit testing for the request-trial-endpoint

* use correct require

* add the translation texts

* fix texts

* remove unnecessary log

* change response status code to forbidden when non cloud

Co-authored-by: Pablo Velez Vidal <pablo.velez@mattermost.com>

einterfaces/cloud.go

@@ -25,6 +25,8 @@ type CloudInterface interface {
 
 	ChangeSubscription(userID, subscriptionID string, subscriptionChange *model.SubscriptionChange) (*model.Subscription, error)
 
+	RequestCloudTrial(userID, subscriptionID string) (*model.Subscription, error)
+
 	// GetLicenseRenewalStatus checks on the portal whether it is possible to use token to renew a license
 	GetLicenseRenewalStatus(userID, token string) error
 	InvalidateCaches() error