Add persistence for localfs datasets

[VladOS95-cyber]

What does this PR do?

Add persistency logic for localfs datasetio provider

• [ ] Addresses issue (#issue)

Test Plan

Please describe:

• tests you ran to verify your changes with result summaries.
• provide instructions so it can be reproduced.

Sources

Please link relevant resources if necessary. https://github.com/meta-llama/llama-stack/issues/539

Before submitting

• [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• [x] Ran pre-commit to handle lint / formatting issues.
• [x] Read the contributor guideline, Pull Request section?
• [ ] Updated relevant documentation.
• [ ] Wrote necessary unit or integration tests.