Support for proxy protocol v2

[UltraInstinct14]

Is your feature request related to a problem? Please describe.
In many NAT nodes used by loxilb, the original sourceIP gets obfuscated at the endpoint. It might result in problem of accounting various things related to the original source such as abuse, DDOS attacks or to keep simple statistical counts.

Describe the solution you'd like
loxilb needs to implement proxy protocol v2. Currently many web-servers already support it

Describe alternatives you've considered
N/A

Additional context
https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

[6547709]

I also need this feature;
Background:
I have always used the architecture of deploying LoadBalancer outside the cluster, which has a clear architecture, short path (LB->PodIP), and better performance (adjusting virtual machine/bare metal configuration). When I use TCP service or Ingress, the source IP (one-arm/FullNAT) cannot be correctly identified;
Requirement:
If LoxiLB can support Proxy protocol V2, these problems can be solved.

[barryiron]

Also in need of this feature, would be great if it can be prioritized. Thanks!