DigitalOcean: Implement TemplateNodeInfo in DO cloud provider CA to support scaling up from zero

[dylanrhysscott]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR updates the DigitalOcean cloud provider implementation to support the TemplateNodeInfo() method which can be utilized by cluster autoscaler to scale up node groups from zero

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

NONE

[k8s-ci-robot]

Hi @dylanrhysscott. Thanks for your PR.

I'm waiting for a github.com 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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[gottwald]

/ok-to-test

[jackfrancis]

/assign @gottwald

[jackfrancis]

/lgtm
/approve

/hold for sign-off from @gottwald

[gottwald]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dylanrhysscott, gottwald, jackfrancis

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• cluster-autoscaler/OWNERS [jackfrancis]

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[gottwald]

/unhold