Async notification for incoming close channel request.
Functions using this handler:
This handler allows to control what to do on close channel notification. Close notification is received when remote peer wants to close some channel.
The handler must return axl_true if the channel can be close, otherwise axl_false must be returned.
If you need to not perform an answer at this function, allowing to deffer the decesion, you can use VortexOnNotifyCloseChannel. That handler will allow to hold the close channel notification, to later complete the request by calling to a finish function.