run commands from web app VM on MC login node

[mflynn-lanl]

@edwins We are adding another workflow manager for running bioinformatics workflows called NextFlow. The way I run it on the MC cluster is to ssh as mcflynn and then sudo su - user and run this command nextflow -C /home/user/EDGEv3/workflows/Nextflow/nextflow_slurm.config run /home/user/EDGEv3/workflows/Nextflow/main.nf. How can we execute that command from the web app VM as user on the login node? I can execute commands on the login node as mcflynn using ssh. For Cromwell we can send a request to the Cromwell server running on the login node (as user)