Support for haproxy map update at runtime

[Mo3m3n]

Map files, which are one of the building blocks of HAProxy Ingress Controller logic, can be updated at runtime (via runtime socket) to avoid haproxy reload. This was added to IC 1.5, however due to the constraints described here https://github.com/haproxytech/kubernetes-ingress/commit/79533942fed8185f40c9a73ae94744696bcca9c9 it was reverted. This issue will track progress of dynamic map update in Ingress Controlller.

[Frankkkkk]

Happy to test the feature once you've got a POC :-)