Use case: exposing single external https frontend and
load balancing services using FQDNs.

Support different ports for internal and external endpoints.

Introduced kolla_url filter to normalize urls like:
- https://magnum.external:443/v1
- http://magnum.external:80/v1



Change-Id: I9fb03fe1cebce5c7198d523e015280c69f139cd0
Co-Authored-By: Jakub Darmach <jakub@stackhpc.com>