MM-12843 Add interactive dialogs (#9816)

* Add interactive dialogs

* Fix unit test

* Updates per feedback

* Fix typo

* Updates per feedback, add icon_url and error returns

* Updates per feedback

* Update per feedback

model/websocket_message.go

@@ -49,6 +49,7 @@ const (
 	WEBSOCKET_EVENT_ROLE_UPDATED            = "role_updated"
 	WEBSOCKET_EVENT_LICENSE_CHANGED         = "license_changed"
 	WEBSOCKET_EVENT_CONFIG_CHANGED          = "config_changed"
+	WEBSOCKET_EVENT_OPEN_DIALOG             = "open_dialog"
 )
 
 type WebSocketMessage interface {