Add mpirun to container

Current state of parallelised simulation runs in container:

• Call via srun (Slurm) works (eve, juwels, barnard)
• When running with mpirun add --bind /tmp:/tmp, see https://issues.guix.gnu.org/71552
• Call with host mpirun works if host OpenMPI version is same as in container (4.x): mpirun -np 2 apptainer exec ogs-petsc.squashfs ogs ....
• Otherwise need to use mpirun from container (added with this MR): apptainer exec ogs-petsc-with-openmpi.squashfs mpirun -np 2 ogs ....
  • may require disabling ssh interconnect: ... mpirun --mca plm_rsh_agent "" ... or via env var OMPI_MCA_plm_rsh_agent=

Will add some documentation later when linked guix issue is resolved.

1. Feature description was added to the changelog