Add mypy to pre-commit

[davorrunje]

Why are these changes needed?

Ideally, pre-commit hook should check types for files that will be checked by mypy in CI. This PR:

• adds to mypy configuration in pyproject.toml the list of files to be checked
• add optional dependency target [types] to setup.py including mypy and other packages that needs to be installed for type checking
• adds mypy check to pre-commit hook
• refactors the existing workflow in CI to use the same configuration as pre-commit

As a consequence, we can run mypy locally on a subset of files as specified in pyproject.toml by simply executing the following command:

$ mypy

Related issue number

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

All modified and coverable lines are covered by tests ✅

Project coverage is 48.32%. Comparing base (6cab643) to head (0d589b4).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2068       +/-   ##
===========================================
+ Coverage   36.88%   48.32%   +11.44%     
===========================================
  Files          68       68               
  Lines        7062     7062               
  Branches     1540     1668      +128     
===========================================
+ Hits         2605     3413      +808     
+ Misses       4228     3360      -868     
- Partials      229      289       +60     

Flag	Coverage Δ
unittests	48.20% <ø> (+11.31%)	⬆️

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[davorrunje]

do we want to change any docker file to preconfigure it?

@sonichi no need, it is automatically setup through existing pre-commit hook