Fix health check from Google's Load Balancer
Fix health check from Google's Load Balancer

This change adds 2 options for windows:
--forward-healthcheck-vip: If true forward service VIP for health check
port
--root-hnsendpoint-name: The name of the hns endpoint name for root
namespace attached to l2bridge, default is cbr0

When --forward-healthcheck-vip is set as true and winkernel is used,
kube-proxy will add an hns load balancer to forward health check request
that was sent to lb_vip:healthcheck_port to the node_ip:healthcheck_port.
Without this forwarding, the health check from google load balancer will
fail, and it will stop forwarding traffic to the windows node.

This change fixes the following 2 cases for service:
- `externalTrafficPolicy: Cluster` (default option): healthcheck_port is
10256 for all services. Without this fix, all traffic won't be directly
forwarded to windows node. It will always go through a linux node and
get forwarded to windows from there.
- `externalTrafficPolicy: Local`: different healthcheck_port for each
service that is configured as local. Without this fix, this feature
won't work on windows node at all. This feature preserves client ip
that tries to connect to their application running in windows pod.

Change-Id: If4513e72900101ef70d86b91155e56a1f8c79719

Kubernetes-commit: 78a507b25647adbf481551c65b900cd817e7a7b3

kubernetes/kube-proxy