[WIP]Cluster template for ipv6

[sayantani11]

What type of PR is this?

What this PR does / why we need it:
This PR adds cluster template for ipv6

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 #
Related to #451

Special notes for your reviewer:

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

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Cluster template for ipv6

[k8s-ci-robot]

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[sayantani11]

/retest

[cpanato]

@sayantani11 thanks for your PR but this does not work today in capg (https://github.com/kubernetes-sigs/cluster-api-provider-gcp/blob/main/api/v1beta1/types.go#L115-L120) we need to implement this support in the service to be able to use ipv6

if you want to implement the code changes that will be awesome, otherwise we can create an issue to add the ipv6 support and close this PR for now

[sayantani11]

@sayantani11 thanks for your PR but this does not work today in capg (https://github.com/kubernetes-sigs/cluster-api-provider-gcp/blob/main/api/v1beta1/types.go#L115-L120) we need to implement this support in the service to be able to use ipv6

if you want to implement the code changes that will be awesome, otherwise we can create an issue to add the ipv6 support and close this PR for now

I can do the necessary changes then, will keep this on hold and will try to do this in a separate PR

[sayantani11]

Will reopen after ipv6 support