[WIP] Add timestamp annotation

[SimonBaeumer]

Add timestamp annotation to CheckResult objects. The goal is to be able to identify when a ComplianceScan is done and has successful update all CheckResults. Additionally, from a client perspective I want to be able to identify when I received all updated CheckResults. Prior to this change it was not possible to know when a check was done if the result didn't changed.

Specification:

• Add compliance.openshift.io/last-scanned-timestamp to CheckResult object
• compliance.openshift.io/last-scanned-timestamp annotation is always updated
• CheckResult objects are updated, even if the Result did not changed.