🚀[FEA]: Support launching through other MPI implementations

[benkirk]

Is this a new feature, an improvement, or a change to existing functionality?

New Feature

How would you describe the priority of this feature request

Medium

Please provide a clear description of problem you would like to solve.

At our site we generally run a proprietary MPI, in this case cray-mpich, so would be benefical to support launching through other MPIs. I will submit a PR that shoudl address recent MPICH variants - at least MPICH-4.x and our cray-mpich.

Describe any alternatives you have considered

OpenMPI is not a viable solution on this particular machine (yet) due to the propriety network.