feat: reference implementation for files API (#2330)

# What does this PR do?
TSIA
Added Files provider to the fireworks template. Might want to add to all
templates as a follow-up.

## Test Plan
llama-stack pytest tests/unit/files/test_files.py

llama-stack llama stack build --template fireworks --image-type conda
--run
LLAMA_STACK_CONFIG=http://localhost:8321 pytest -s -v
tests/integration/files/

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

@@ -0,0 +1,31 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from typing import Any
+
+from pydantic import BaseModel, Field
+
+from llama_stack.providers.utils.sqlstore.sqlstore import SqliteSqlStoreConfig, SqlStoreConfig
+
+
+class LocalfsFilesImplConfig(BaseModel):
+    storage_dir: str = Field(
+        description="Directory to store uploaded files",
+    )
+    metadata_store: SqlStoreConfig = Field(
+        description="SQL store configuration for file metadata",
+    )
+    ttl_secs: int = 365 * 24 * 60 * 60  # 1 year
+
+    @classmethod
+    def sample_run_config(cls, __distro_dir__: str) -> dict[str, Any]:
+        return {
+            "storage_dir": "${env.FILES_STORAGE_DIR:" + __distro_dir__ + "/files}",
+            "metadata_store": SqliteSqlStoreConfig.sample_run_config(
+                __distro_dir__=__distro_dir__,
+                db_name="files_metadata.db",
+            ),
+        }