Add throwing callable wrapper

[Skyline-23]

This pull request introduces a new way to call Python functions from Swift that surfaces Python exceptions as Swift errors, rather than trapping. This allows developers to handle Python errors using Swift's try/catch mechanism, making error handling more robust and idiomatic in Swift. The changes include a new wrapper type, an extension property for easier access, and corresponding unit tests.

New error-handling callable support:

• Added a throwingCallable property to PythonObject, which returns a ThrowingDynamicCallable wrapper. This allows users to opt-in to error handling via try/catch when calling Python functions from Swift.
• Introduced the ThrowingDynamicCallable struct, a dynamic-callable wrapper around PythonObject that throws Swift errors when Python exceptions are raised, instead of trapping. This struct provides several dynamicallyCall methods for calling Python functions with positional or keyword arguments.

Testing:

• Added a new test, testThrowingCallableWrapper, to verify that throwingCallable correctly returns results for valid calls and throws Swift errors for Python exceptions, including checking the exception type.