Convert to use V1 Ingress API

[swetharepakula]

This is a large PR and touches many parts of the code. Currently it is based on #1415 , which I will update soon.

While reviewing please keep the following in mind:
1. E2E tests

• Tests need to pass for Clusters 1.15 - 1.18 if applicable (where v1 API is unavailable)
• Tests need to pass for Clusters 1.22+ (where v1beta1 API is removed)

2. Ingress Resource Changes
Service.Port (on the Ingress resource) used to be of type IntOrString, but now it is:

type ServiceBackendPort struct with {
    Number int32
    Name string
}

• Internally the ServiceBackendPort will be used throughout the controller
• Watch out for the .String() on that port as before it would return the value in string format but now will return the entire struct

3. Any accidental change in behavior due to the conversion or the Service.Port change that was made

4. Backend services in the Ingress spec can now be nil

[k8s-ci-robot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
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[swetharepakula]

/cc @prameshj @skmatti @spencerhance
/assign @freehan

[k8s-ci-robot]

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/cc @prameshj @skmatti @spencerhance
/assign @freehan

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[liggitt]

in main.go, I'd suggest replacing this:

	ingClassEnabled := flags.F.EnableIngressGAFields && app.IngressClassEnabled(kubeClient)

with a check that requires v1 Ingress and IngressClass and exits with an error if those APIs aren't available, rather than acquiring leader election

[liggitt]

is there a check early in main.go now to ensure that v1 Ingresses are supported? would that make sense to add to ensure we don't get in a state where we're running with v1 informers that won't sync (xref kubernetes/kubernetes#99840 (comment))

also, this appears to be blocking a successful run of the kubernetes/kubernetes PR that tests without any beta APIs enabled (the gce cluster won't start with this controller crashlooping on extensions/v1beta1 being missing)

[swetharepakula]

There was one more call to ExtensionsV1beta1() that I missed: https://github.com/kubernetes/ingress-gce/blob/master/cmd/glbc/app/namer.go#L164 which was causing the failure in #99840.

I have fixed it in this PR. Once this is merged and a release is cut I will update the image being used in the glbc addon.

[swetharepakula]

Only unaddressed comment is about the startup checks for IngressClass and the IngressGAFields. Since this is already a large PR with a lot of subtle changes, I will address the remaining comment in a followup PR.

Otherwise I think this PR is ready for a final set of reviews and is almost ready to be merged.
Thanks everyone for all the reviews and feedback!

[freehan]

/lgtm
/approve

[freehan]

/lgtm

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[liggitt]

happy to see the land. is the next step a v1.11.2 and a bump in kubernetes/kubernetes?

[swetharepakula]

We will be cutting a 1.12 release soon. Just finishing up some testing before we cut the tag so should be ready in about a day.

[swetharepakula]

kubernetes/kubernetes#101772 updates the glbc image which should unblock kubernetes/kubernetes#99840