warn about costly scan scheduling in Helm output

[matheusfm]

Description

This PR includes a warning in the Helm output if a scan appears to be scheduled to run more frequently than the recommendation.

It also fixes the helm template for ClusterScans, checking the API Version before calling the lookup function.

How has this been tested?

Trying installing Zora with different schedules for each scan.

helm upgrade --install zora charts/zora/ -f /tmp/values.yaml -n zora-system --create-namespace

This is the values.yaml:

clusterName: kind
scan:
  # misconfiguration:
  vulnerability:
    # At every minute
    # schedule: "* * * * *"

    # At every minute on Wednesday
    # schedule: "* * * * 4"

    # At 00:00 on Wednesday (weekly)
    # schedule: "0 0 * * 4"

    # At 00:00 on day-of-month 1 (monthly)
    # schedule: "0 0 1 * *"

    # At every minute on day-of-month 1
    # schedule: "* * 1 * *"

    # Every hour at every 30th minute
    # schedule: "*/30 * * * *"

    # Every hour at every minute (range of values)
    # schedule: "0-59 * * * *"

    # Every hour at minute 15 and 45
    # schedule: "15,45 * * * *"

    # Every hour at minute 0
    # schedule: "0 * * * *"

    # At minute 0 past hour 12 and 18
    # schedule: "0 12,18 * * *"

    # At 10:00
    # schedule: "0 10 * * *"

    # Every hour at minute 0 on day-of-month 5
    schedule: "0 * 5 * *"

Unfortunately helm template does not render NOTES.txt (https://github.com/helm/helm/issues/6901)

Checklist

• [x] I have labeled this PR with the relevant Type labels
• [x] I have documented my code (if applicable)
• [ ] My changes are covered by tests