Proper support for IngressClass

[rainest]

Is there an existing issue for this?

• I have searched the existing issues

Problem Statement

As of 2.1, KIC treats ingressClassName identically to the deprecated class annotation: if the listed class matches the controller's configured class, it ingests the Ingress.

Ingress v1 should actually interact with IngressClass resources in some fashion.

Proposed Solution

• Implement an IngressClass controller
• Restore support for classless ingresses per https://kubernetes.io/docs/concepts/services-networking/ingress/#default-ingress-class
• Implement Service-upstream default controlled by IngressClass parameters #1131

Additional information

No response

Acceptance Criteria

• Service-upstream default controlled by IngressClass parameters #1131 is done to be handled in that issue.
• classless ingresses (as described above) working

[rainest]

Closing this as we already have a separate issue for the remaining functionality without plans to start work on it immediately. #2292 and #2313 cover the functionality that wasn't tracked elsewhere.