Test different variants of K8s Services in conformance testing

[dprotaso]

What would you like to be added:

We should add conformance tests that ensure Gateway API works well with different variants of K8s Services, Endpoint, EndpointSlices

Short List Variants

• Service - with selector
• Service - with selector, endpoint slice mirror disabled
• Headless Service - with manual endpoints (and their different types)
• Headless Service - with manual endpoint slices (and their different types - ie. FQDN)

Why this is needed:

Different platforms that build on-top of K8s will utilize Services in different ways to suit their needs - it would be great to know Gateway conformance supports these variants. ie. some implementations currently don't track EndpointSlices which is pretty fundamental as they've been stable for numerous years

[Xunzhuo]

/assign
/remove-help