Matlab testing on github

[jmlarson1]

Given many POptUS methods are in matlab, it would be nice to have GitHub Actions run matlab tests. (An example file/repo can be seen here:

https://github.com/libprima/prima/actions/runs/4845254547/workflow

Matlab doesn't have packaging capabilities similar to python, so hopefully the setup/testing is easier.

Currently, to run matlab tests (as a part of pounders code coverage checks) in IBCDFO, navigate to IBCDFO/pounders/m/tests and modify the paths to locations of the minq and BenDFO files in IBCDFO/pounders/m/tests/setup_paths.m. Then open matlab and run make_coverage.

Such testing can stay at the "method level". That is, I don't think there is a need to jointly run these tests locally (or GH-actions).