Run Wuestebach test case in CI

[kvrigor]

It would be good to run the 1x1 Wuestebach case as a last step in CI.yml. This case only requires 1 CPU which makes it easy to run on GitHub's Ubuntu CI runners. Also sbatch/srun won't be necessary--for single-CPU cases, running eclm.exe directly works.

This is how I think this could be done:

1. Generate reference Wuestebach outputs via CLM5 (this should be done offline).
2. Compute statistics (e.g. mean, stddev) of the relevant Wuestebach output variables. This should be done via shell commands (e.g. cdo) or shell script (Python, R, etc.). The results can be saved to a file for later comparison with eCLM.
3. Add these steps in CI.yml:
   a. Run the 1x1 Wuestebach case.
   b. From the generated history files, compute the same statistics as in Step 2.
   c. Compare the results from the precomputed statistics of the reference CLM5 run.
   d. CI test should pass if absolute error <= tolerance for all variables. Otherwise the test is marked as failed.

[AGonzalezNicolas]

I would compare the outputs variables for a range of time as we did in Issue 103 and compute the maximum errors of those outputs.
The maximum error for each output variable should pass the tolerance test.