Cumulus MFEM/MOOSE build scripts

[Giannis95]

Create two .sh files:

1. Pre-fetch the required submodules on the login node (with internet access) in a directory away from /moose
2. Using the pre-fetched submodules, build MFEM/MOOSE by running the ./scripts/update_and_rebuild_.sh on a compute node. Here, we need to have options to submit through the scheduler or build in an interactive session

Additionally:

1. Add documentation of how to run the two script files and their detailed descriptions.

The MOOSE directory is assumed to be already cloned.