✨ Add single stack IPv6 support

[jsturtevant]

What this PR does / why we need it:
Adds ipv6 support. To use, set CLUSTER_TEMPLATE to cluster-template-ipv6.yaml.

kubectl --kubeconfig=./kubeconfig get nodes -o wide
NAME                              STATUS   ROLES    AGE   VERSION   INTERNAL-IP              EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION     CONTAINER-RUNTIME
ipv6-test-2-control-plane-94sb4   Ready    master   29m   v1.18.8   2001:1234:5678:9abc::5   <none>        Ubuntu 18.04.5 LTS   5.3.0-1034-azure   containerd://1.3.4
ipv6-test-2-control-plane-c5kp6   Ready    master   25m   v1.18.8   2001:1234:5678:9abc::6   <none>        Ubuntu 18.04.5 LTS   5.3.0-1034-azure   containerd://1.3.4
ipv6-test-2-control-plane-zjxw4   Ready    master   32m   v1.18.8   2001:1234:5678:9abc::4   <none>        Ubuntu 18.04.5 LTS   5.3.0-1034-azure   containerd://1.3.4
ipv6-test-2-md-0-wgmtf            Ready    <none>   29m   v1.18.8   2001:1234:5678:9abd::5   <none>        Ubuntu 18.04.5 LTS   5.3.0-1034-azure   containerd://1.3.4
ipv6-test-2-md-0-z6lwq            Ready    <none>   29m   v1.18.8   2001:1234:5678:9abd::4   <none>        Ubuntu 18.04.5 LTS   5.3.0-1034-azure   containerd://1.3.4

Co-authored by @jsturtevant, @CecileRobertMichon and @aramase.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #318

Special notes for your reviewer:

Before merging needs:

• unit tests fixed
• e2e tests
• docs

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

Add single stack IPv6 support
Deprecate VNet and Subnet CirdrBlock in favor of CIDRBlocks

[k8s-ci-robot]

Hi @jsturtevant. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[devigned]

/ok-to-test

[jsturtevant]

it is now working but currently has issues with route creation #682

[CecileRobertMichon]

rebased

[devigned]

/lgtm

Great collaboration folks!

[nader-ziada]

awesome work all, even though we will get probably get merge conflicts now :D

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: nader-ziada

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[nader-ziada]

looks like something timed out

/test pull-cluster-api-provider-azure-e2e

[CecileRobertMichon]

Had to change the ipv6 template to use key: worker-node-azure.json for the worker nodes after #955 merged.

[k8s-ci-robot]

@jsturtevant: The following test failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-cluster-api-provider-azure-apidiff	c05182f	link	/test pull-cluster-api-provider-azure-apidiff

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[nader-ziada]

/lgtm