SessionAffinity in Service

[costinm]

Another potential 'on by default' and 'do not break apps' issue: https://kubernetes.io/docs/reference/networking/virtual-ips/#session-affinity

In L4 mode - I think we may need some table to maintain the persistence. For Waypoints - this may need to use the header-based persistence filters in Envoy that we just added support for. Ztunnel would likely need to keep track of L7 Service with affinity and track and add the persistence header.

Also we may consider using this affinity as another way to trigger header-based persistence with Sidecars and Gateways.