Is your feature request related to a problem? Please describe.

Based on the discussion on this issue, #7736 eventually we would want to move all the metrics that cert manager exposes through a collector format. This makes it more concise and the code becomes more readable as the collector queries the API.

Initially this migration would involve the refactoring of the above PR and then subsequently more PRs would address migration of other metrics.

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Additional context

Environment details (remove if not applicable):

• Kubernetes version:
• Cloud-provider/provisioner:
• cert-manager version:
• Install method: e.g., helm/static manifests

/kind feature