feat: gke zonal cluster support

[FrancoisKlieberOrange]

What type of PR is this?

What this PR does / why we need it:

This PR allow the creation of zonal GKE cluster. Before only regional GKE cluster could be created.

TODOs:

• [ x] squashed commits
• [x ] includes documentation
• [ x] adds unit tests

Release note:

feat: gke zonal cluster support

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: FrancoisKlieberOrange (214964d)

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[k8s-ci-robot]

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[cpanato]

/ok-to-test

[richardcase]

/lgtm

[damdo]

/assign @cpanato for approval

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In response to this:

/assign @cpanato for approval

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[cpanato]

thanks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, FrancoisKlieberOrange

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Needs approval from an approver in each of these files:

• OWNERS [cpanato]

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