Meta: Couple NN implementation of CLUBB into CAM

[jatkinson1000]

• Obtain the M2LInES Fork of CLUBB as a submodule in CAM
  • Requires selection of appropriate CAM version to work with
• Successfully build with FTorch coupling
  • Requires adaptation of the CIME build system to handle
  • Tests to verify that the FTorch coupling is working as expected
    E.g. running a basic net to generate [1, 2, 3, 4] or similar.
• Coupling of new CLUBB scheme into CAM
  • Matching interface and providing any necessary switching arguments and model paths
  • Structuring code to run in piggybacked configuration