Hash the Names of Managed Infra Resources

[danehans]

EG currently generates names of managed envoy infra. The names are generally constructed of gateway namespace, gateway name, etc. The names can be long and potentially exceed the allowed length (63 chars) of a Kube name. Instead, and similar to Kube, the name should be generated from a hash.

xref: #404

[danehans]

Added bug label due to #434.

[danehans]

When using hashed names for managed resources, users will need to use --selector to correlate managed resources to a Gateway. For example:

$ kubectl get deploy -n envoy-gateway-system --selector=gateway.envoyproxy.io/owning-gateway-name=eg,gateway.envoyproxy.io/owning-gateway-namespace=default
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
envoy-ef185hc   1/1     1            1           2m14s

It might make debugability a bit easier if we had one label that was namespace/name. @arkodg @skriss @LukeShu @youngnick thoughts?

[danehans]

A similar approach will be needed for the ports of the managed Envoy serivce.

[arkodg]

I prefer if we used a hybrid approach in naming - envoy-<40-50 char namespaced name>-<short-hash> to improve debug speed.

[Alice-Lilith]

I'll take this one on. Should have some bandwidth in the coming week.