optionally prefix singularity execution with mpirun/mpiexec

[tbugfinder]

Proposal:

Add an option to singularity configuration settings like singularity.prefixcmd which is empty by default and could be configured to e.g. a string containing mpirun or mpiexec.
It might also be possible to use a bash alias singularity="mpirun singularity", though.

Ref:
https://github.com/nextflow-io/nextflow/blob/master/modules/nextflow/src/main/groovy/nextflow/container/SingularityBuilder.groovy

Discussed in #3064

^{Originally posted by tbugfinder July 25, 2022}
Hello,

in some cases in might be beneficial to execute a singularity container within a mpirun command.
I couldn't find the option to do with with the current implementation.

Any hint would be appreciated.

Thanks & Best

Josef