Is your feature request related to a problem? Please describe.
If an experiment stops due to some reason (network issue etc which causes yival to terminate), we lose all the experiment results, and have to run it again. This would be costly when we are running gpt-4 based evaluation for many data points.

Describe the solution you'd like
Save the experiment state and results on disk when running experiment, and add the ability to resume the experiment to yival.

Describe alternatives you've considered
It might help if we keep a cache of LLM calls. But I think a cache is not always favorable as sometimes we want LLM to generate new output on every request.