Private Datasets: GQL API: Ability to change dataset visibility

[s373r]

Description

Closes: https://github.com/kamu-data/kamu-cli/issues/724

Checklist before requesting a review

• [ ] Unit and integration tests added
• [ ] Compatibility:
  • [ ] Network APIs: ✅
  • [ ] Workspace layout and metadata: ✅
  • [ ] Configuration: ✅
  • [ ] Container images: ✅
• [ ] Documentation:
  • [ ] Changelog: ✅
  • [ ] Public documentation: ✅
• [ ] Downstream effects:
  • [ ] kamu-node: ✅