feat(BA-4141): Migrate Image legacy GQL mutation to strawberry

[jopemachine]

resolves #8416 (BA-4141)

Legacy Mutation	Implemented	Reason if not implemented
AliasImage	✅	alias_image (image_id-based)
ClearImages	❌	Action exists in container_registry service, not image service.
DealiasImage	✅	dealias_image
ForgetImage	✅	forget_image (image_id-based)
ForgetImageById	✅	forget_image
ModifyImage	✅	modify_image (image_id-based)
PurgeImageById	✅	purge_image
RescanImages	❌	Action in container_registry service. Requires background task manager.
UntagImageFromRegistry	✅	untag_image_from_registry

Checklist: (if applicable)

• Milestone metadata specifying the target backport version
• Mention to the original issue
• Installer updates including:
  • Fixtures for db schema changes
  • New mandatory config options
• Update of end-to-end CLI integration tests in ai.backend.test
• API server-client counterparts (e.g., manager API -> client SDK)
• Test case(s) to:
  • Demonstrate the difference of before/after
  • Demonstrate the flow of abstract/conceptual models with a concrete implementation
• Documentation
  • Contents in the docs directory
  • docstrings in public interfaces and type annotations

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📚 Documentation preview 📚: https://sorna--8417.org.readthedocs.build/en/8417/

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📚 Documentation preview 📚: https://sorna-ko--8417.org.readthedocs.build/ko/8417/