CommonPredicates returns the predicate which filter out the changes done to any field except for spec (e.g.

DeleteOnly returns a predicate that will filter out everything except the Delete event.

EventHandlerWithDelete is an extension of EnqueueRequestForObject that will _not_ trigger a reconciliation for a Delete event.

ResourcesHandler is a special implementation of 'handler.EventHandler' that checks if the event for WatchedObject must trigger reconciliation for any Operator managed Resource (AtlasProject, AtlasCluster etc).

ResourceWatcher is the object containing the map of watched_resource -> []dependant_resource.

WatchedObject is the object watched by controller.