Conformance: Add coverage for AttachedRoutes, ensuring count is accurate regardless of Listener or Route validity

[sunjayBhatia]

What would you like to be added:

Following on from #2396 we should add conformance that covers the exact semantics defined in the API for implementations when setting the Gateway Listener status AttachedRoutes count field.

Namely:

• AttachedRoutes should be set on Listeners that are valid or invalid
• The count of AttachedRoutes should include Routes that are valid or invalid

Why this is needed:

The spec now defines the AttachedRoutes field to document the number of Route resources that are successfully related to a Gateway, regardless of the validity of either side of the relationship.

[shaneutt]

We're going to try to get this into v1.0.0, but we don't consider it a blocker for that release.

If someone has some extra time and wants to work on this one, it would be appreciated.

/help

[k8s-ci-robot]

@shaneutt:
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In response to this:

We're going to try to get this into v1.0.0, but we don't consider it a blocker for that release.

If someone has some extra time and wants to work on this one, it would be appreciated.

/help

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[danehans]

/assign