fix(autogen-core): pass positional-only tool arguments positionally - #8415

Why are these changes needed?

FunctionTool builds a valid argument schema for an annotated function with positional-only parameters, but run() passed every argument by keyword. Validation therefore succeeded and the call then failed with TypeError:

TypeError: scale() got some positional-only arguments passed as keyword arguments: 'value'

This affects sync and async functions, and an injected cancellation_token declared as positional-only.

run() now collects positional-only parameters and passes them positionally, in signature order, keeping all other parameters as keywords. Sync functions still link the future only when the wrapped function does not take the cancellation token, as before.

Related issue number

Closes #8319

Checks

• I've added tests corresponding to the changes introduced in this PR.
• I've made sure the relevant auto checks have passed.

Verification

Tests added to python/packages/autogen-core/tests/test_tools.py:

• sync and async functions with positional-only parameters and a keyword-only default;
• a positional-only parameter whose default is used when it is omitted;
• a positional-only injected cancellation_token;
• a mix of positional-only and keyword parameters.

Each case fails on the unchanged implementation for the reported reason and passes with the change.

$ uv run --with pytest-asyncio --with pytest-mock --package autogen-core \
    pytest packages/autogen-core/tests -q \
    --ignore=packages/autogen-core/tests/test_json_to_pydantic.py \
    --ignore=packages/autogen-core/tests/test_model_context.py
147 passed

$ uv run --with ruff==0.4.8 ruff check <changed files>
All checks passed!

(The two ignored files need autogen-ext, which is not part of this package's test environment.)