promise: check_port_listening is now available with new promise mechanism

This promise will replace the old check_port_listening promise (https://lab.nexedi.com/nexedi/slapos/blob/master/slapos/recipe/check_port_listening.py). See https://www.erp5.com/slapos-TechnicalNote.General.SlapOS.Monitoring.Specifications for how to instantiate this promise in buildout.