This builds on top of https://issues.redhat.com/browse/SDN-4939 

Goal of this card is to implement the services workflow for user-defined networks - for host/external-> services flows

• Check Services aspect in the KEP
• add logic to ensure services are accessible on the user-defined network from host and external entities on both gateway modes
• accordingly for services update LBs on switches and routers for the user-defined/secondary network network topology
• add flows on br-ex to sway service traffic into the correct VRFs in LGW mode and correct patch port in SGW mode
• add tests for all combos here
• use cgroups for host-networked service access isolation blocking to other networks its not part of check KEP for design details on this

End goal here is: Only add support for southbound->services logic on user-defined network for the pods. Other things will have other cards. Please work with other assignee as a "services-design-sub-group" so that you also have your potential reviewer in your group.

TL;DR: traffic flows that should be supported here:

1. host/external->clusterip (w & w/ITP=local)
2. host/external->loadbalancerVIP (w & w/ ETP=local)
3. host/external->externalIP
4. host/external->nodePort -> sameNode/otherNode