Add ScheduledComplianceScan API

[AleksandarSavchev]

How to categorize this PR?

/area compliance
/kind enhancement

What this PR does / why we need it:
This PR add the ScheduledComplianceRun API:

apiVersion: diki.gardener.cloud/v1alpha1
kind: ScheduledComplianceScan
metadata:
  name: example-scheduledcompliancescan
spec:
  schedule: "0 0 * * *" # cron format
  successfulScansHistoryLimit: 3 # number of completed scans to keep
  failedScansHistoryLimit: 1 # number of failed scans to keep
  scanTemplate:
    spec:
      rulesets:
        - id: security-hardened-k8s
          version: v0.1.0
          options:
            rules:
              configMapRef:
                name: diki-options
                namespace: kube-system
status:
  active: <obj ref> # active ComplianceScan (object reference)
  lastScheduleTime: "2025-12-31T23:59:59Z"
  lastCompletionTime: "2025-12-31T23:59:59Z"

Which issue(s) this PR fixes:
Part of #3

Special notes for your reviewer:

Release note:

Add the `ScheduledComplianceScan` API, used to schedule `ComplianceScan` resources.

[georgibaltiev]

Thank you!
I have only one nit, and a few questions that I would like to discuss, possibly for future enhancements.

[georgibaltiev]

/lgtm

[gardener-prow]

LGTM label has been added.

Details

Git tree hash: 1a2c3257b4bce95e113ce0fea3f0d86166530eeb

[dimityrmirchev]

/approve

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dimityrmirchev

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