Add MATLAB_UPDATE argument to dockerfile

[PVDecker1]

I would consider this an enhancement request.

There are cases where it is useful to test/troubleshoot code across release updates, but none of the dockerfiles have a means of installing a specific update of any given release.

It can be done fairly simply by adding a MATLAB_UPDATE argument, then appending it to MATLAB_RELEASE during the mpm call. That is what I do to accomplish update-specific MATLAB builds at least, although I would prefer TMW implement this behavior.