support for kube-vip liveness probe

[rptaylor]

With https://github.com/kube-vip/kube-vip/pull/1079/files it is possible to add an env var e.g.

    - name: health_check_port                                                                                                                                                
      value: "9989"

then on a node you can

$ curl http://localhost:9989/healthz
OK

so the chart could use this to define a liveness probe (a readiness probe is not applicable).

As noted the port would have to be selected carefully since kube-vip uses hostNetwork - or just define an arbitrary default port, but have the probe disabled by default.