Add documentation for running MESSAGEix on UniCC

[measrainsey]

WIP: migrate my internal guide and documentation on how to run MESSAGEix on the cluster (UniCC) and make some modifications

How to review

For @khaeru and/or @glatterf42 : Read the diff and note that the CI checks all pass.

PR checklist

• Continuous integration checks all ✅
• Add or expand tests; coverage checks both ✅
• Add, expand, or update documentation.
• Update doc/whatsnew.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.7%. Comparing base (c782c30) to head (6b4cd85).

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #279     +/-   ##
=======================================
- Coverage   77.6%   76.7%   -1.0%     
=======================================
  Files        211     211             
  Lines      16079   16079             
=======================================
- Hits       12481   12333    -148     
- Misses      3598    3746    +148     

see 7 files with indirect coverage changes

[glatterf42]

Thanks for this extensive guide! Skimming over it, I thought of just a few notes :)

[glatterf42]

Even if it's a demo, I'm not sure we should post the contents to our docs.

[glatterf42]

Suggested change

	I usually request lots of run time (20 hours) and lots of memory (100 GB) because I don't want my job to for those reasons.
	I usually request lots of run time (20 hours) and lots of memory (100 GB) because I don't want my job to fail for those reasons.

[glatterf42]

It's great to have a section like this, but if the cluster becomes more heavily used, there are more considerations for setting these parameters: in general, slurm will try to optimize its load so that it's running almost always at full capacity. This makes it harder to request lots of resources for extended amounts of time because the system will not be able to squeeze in such a task with other tasks, thus it will likely take longer for the task to be picked up.
I don't know if UniCC is already experiencing the kind of load to make these considerations necessary, but if/once it does, we would likely want to optimize these parameters further to request the minimum necessary that still reduces the run time :)