merge load data source async and sync together using a flag

[Shashankss1205]

Reference Issues/PRs

See also: feature/data_management

What does this implement/fix? Explain your changes.

This PR merges the load_data_source and load_data_source_async tools into a single, unified load_data_source tool utilizing a run_async boolean flag:

• Merged the tool functions into load_data_source_tool(config, run_async=False) in data_tools.py.
• Updated the fastmcp schema and call routing in server.py to route both types of operations seamlessly.
• Removed the separate load_data_source_async tool registration and files exports.
• Updated all associated unit tests in test_async_data_loading.py to leverage the new unified tool with the run_async=True flag.

This significantly simplifies the MCP API surface while preserving complete flexibility for loading large custom files in the background without timeout issues.

Does your contribution introduce a new dependency? If yes, which one?

No.

What should a reviewer concentrate their feedback on?

• Verify that all 189 unit tests pass perfectly via make check.
• Verify that FastMCP routing is correctly accepting and passing the run_async parameter to the core tool handler.

Any other comments?

N/A

PR checklist

For all contributions

• I've added unit tests and made sure they pass locally (make check).
• I've added the tool to the online documentation in docs/source/.
• I've updated the existing example scripts or provided a new one to showcase how my tool works in examples/.