Generate crd-generator annotation for source type

[matteriben]

Description

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

[andreaTP]

Unless there is a compelling use case we do not want to emit SchemaFrom in the generated code.

SchemaFrom is a workaround to handle edge cases and we do not want to expand its usage in the wild.

Let me know if I'm missing something in this analysis.
cc. @shawkins