More async tool fixes

[yenif]

Why are these changes needed?

Fixes for #1174, also includes the bug fix in #1201

Started thinking about test coverage, a little awkward to exercise correctly.

Also there is odd interplay between sync/async tool funcs and if that conversations is calling through the sync or async send/receive methods.

Current setup

• sync convo calls sync functions and tools
• async convo calls async functions and tools, if no async function or tools then it calls sync functions and tools

Previously

• sync convo calls sync functions
• async convo calls sync and async function

I see a similar thing happen with check_termination_and_human_reply when running in async, it gets called twice if a_human_reply returns None for no human input.

I think https://github.com/miguelgrinberg/promisio can resolve the issue by providing the same interface for both sync and async functions. But that is a much bigger change and likely not backward compatible.

Related issue number

closes #1174

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov-commenter]

Codecov Report

Attention: 27 lines in your changes are missing coverage. Please review.

Comparison is base (b548e55) 30.38% compared to head (0fe43fe) 50.03%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
autogen/oai/client.py	77.14%	15 Missing and 9 partials ⚠️
autogen/agentchat/conversable_agent.py	40.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1204       +/-   ##
===========================================
+ Coverage   30.38%   50.03%   +19.65%     
===========================================
  Files          32       32               
  Lines        4302     4355       +53     
  Branches      994     1066       +72     
===========================================
+ Hits         1307     2179      +872     
+ Misses       2901     1963      -938     
- Partials       94      213      +119     

Flag	Coverage Δ
unittests	49.94% <75.89%> (+19.60%)	⬆️

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[davorrunje]

Another option would be allowing both async and sync functions to be called using something like asyncer (https://github.com/tiangolo/asyncer). However, I would not add it as an additional dependency but rather rewrite it for our needs (that ~300 lines of code altogether and can be done in a day).

[davorrunje]

LGTM.

I think we need to add tests for all of the new functionality, but that should be another PR because these fixes cannot wait.