chore(core): improve typing of messages utils functions

[Christophe Bornet (cbornet)]

With this we get the correct types for _runnable_support annotated functions.

• return list[BaseMessage] when messages is not None
• return Runnable when messages is None
• typing of function args

[Christophe Bornet (cbornet)]

It found some incorrect typing 😃

[codspeed-hq]

CodSpeed Performance Report

Merging #34225 will not alter performance

_{Comparing cbornet:messages-utils-types (6b95a89) with master (80c3970)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 13 untouched
⏩ 21 skipped¹

Footnotes

1. 21 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Christophe Bornet (cbornet)]

There is now typing for _runnable_support annotated method args.