Add persistence for localfs datasets (#557)

# 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](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

llama_stack/providers/inline/datasetio/localfs/config.py

@@ -5,5 +5,14 @@
 # the root directory of this source tree.
 from pydantic import BaseModel
 
+from llama_stack.distribution.utils.config_dirs import RUNTIME_BASE_DIR
+from llama_stack.providers.utils.kvstore.config import (
+    KVStoreConfig,
+    SqliteKVStoreConfig,
+)
 
-class LocalFSDatasetIOConfig(BaseModel): ...
+
+class LocalFSDatasetIOConfig(BaseModel):
+    kvstore: KVStoreConfig = SqliteKVStoreConfig(
+        db_path=(RUNTIME_BASE_DIR / "localfs_datasetio.db").as_posix()
+    )  # Uses SQLite config specific to localfs storage