Add initial type check CI

[jackgerrits]

Why are these changes needed?

This adds an initial CI that targets known clean modules.

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 37.09%. Comparing base (78a5a6b) to head (757b5d2).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1882   +/-   ##
=======================================
  Coverage   37.09%   37.09%           
=======================================
  Files          64       64           
  Lines        6834     6834           
  Branches     1502     1502           
=======================================
  Hits         2535     2535           
  Misses       4082     4082           
  Partials      217      217           

Flag	Coverage Δ
unittests	37.09% <ø> (ø)

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[jackgerrits]

@ekzhu @davorrunje this is ready to review