Fix crash when handling complex type hints in function signatures

[praharsh777]

Hello!! This PR resolves an issue where Bowler would crash when transforming functions with complex type annotations like typing.List[str].

🐞Problem:
When processing code like:
"""
def foo(bar: typing.List[str]):
pass
"""
Bowler raised:
""" AttributeError: 'Node' object has no attribute 'value' """

✅My Solution for the above problem :
Updated FunctionArgument.build() to:
-Safely check whether the annotation is a Leaf or Node
-Use .value for Leaf, str(...) for complex Nodes
-Clone values safely and avoid AttributeError

🧪Tests Added
New test file: test_typehints.py
Verifies Query(...).add_argument(...) works correctly with functions using typehints like typing.List[str]

🔄Code Changes
In imr.py:
Improved logic in FunctionArgument.build() for safe annotation parsing
In query.py:
Added a lightweight inline test for typing.List[str]
In tests/test_typehints.py:
Full test case validating transformation on typehinted functions

🧵Related Issue
Closes #129

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[praharsh777]

Hi, I've signed the CLA. Just waiting for the status to update. Thanks!

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[praharsh777]

Hi @facebook-github-bot , just checking in to see if this PR needs any changes. Happy to help!