* feat(assist): splitted socket methods in ee/websockets
* feat(assist): splitted socket methods in ee/websockets-cluster
* feat(assist): moved socket handlers to separate file
* feat(assist): changed the way how to get ws server
* feat(assist): use method to get io server instead of global object
* feat(assist): removed duplicated code from ee assists
* feat(assist): removed copy-paste http handlers
* feat(assist): added getServer call for some http handlers
* feat(assist): added creds=true to cors settings
* feat(backend): added debug log flag to assist stats
