Refactor from_defaults to Use tool_metadata_from_defaults for Cleaner and More Efficient Metadata Handling

[johnmalek312]

I added a separate helper method, tool_metadata_from_defaults, to handle metadata extraction instead of doing it inline in FunctionTool.from_defaults(). This makes the code cleaner and keeps metadata handling separate from tool initialization. Now, from_defaults() calls this method when no tool_metadata is provided.

This Helps When Wrapping Tools

import functools

def my_decorator(fn):
    original_metadata = FunctionTool.tool_metadata_from_defaults(fn)

    @functools.wraps(fn)
    def wrapper(*args, **kwargs):
        print("Wrapper: Pre-processing")
        result = fn(*args, **kwargs)
        print("Wrapper: Post-processing")
        return result

    return FunctionTool.from_defaults(fn=wrapper, tool_metadata=original_metadata)

This makes from_defaults() more readable while ensuring wrapped functions retain their original metadata without having to create a seperate tool and extracting metadata from.