coding agent; logging

[sonichi]

Why are these changes needed?

• Implement a simple coding agent. Documentation is not added as the design could change in future.
• Added a test example where the coding agent is able to recover from failure.
• Added an experimental support for logging, documentation and test cases.

Related issue number

Checks

• I've used pre-commit to lint the changes in this PR, or I've made sure lint with flake8 output is two 0s.
• I've included any doc changes needed for https://microsoft.github.io/FLAML/. See https://microsoft.github.io/FLAML/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.

[BeibinLi]

LGTM

[qingyun-wu]

looks good to me.

[victordibia]

+1 on the use of a code block pattern here to extract code. I do this and some other light postprocessing checks for a separate project where I generate and execute code. For example, I require the model to do code infilling instead of freeform generation. So I know what the last line of the code should be and I can do additional extraction based on that.

[victordibia]

Looks like a good starting point for these sort of functionality.