Provide starting and ending times of each problem and each run

[zaikunzhang]

Hi @ragonneau and @OptHuang,

We need to record the starting and ending times of each problem and each run, and make them available to the user.

Motivation:

When running tests on GitHub Actions, some problems may not end due to various reasons, e.g., errors or overtime. We need to know which problems they are and exclude them from future tests. It may also be necessary to know which problems take excessively much time and possibly exclude them.

This may not be as trivial as you imagine when you implement it. For example, here are two difficulties in MATLAB.

1. tic and toc do not work in parfor loops.
2. You may think of including the starting and ending times in the return. This is an excellent idea but will not work in MATLAB. Imagine that the code encounters a segfault somewhere. MATLAB will crash and hence we would not have the chance to return --- try ... catch will not work in this situation. I guess this is not unique to MATLAB.

I have an implementation but I prefer you think about it yourself. Maybe you will come up with a better idea.

Thanks.