Complete CCPPization of CAM7 hb_free_atm: add regression test

[jimmielin]

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Originator(s): @jimmielin
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Companion PR: ESCOMP/atmospheric_physics#414

Description (include the issue title, and the keyword ['closes', 'fixes', 'resolves'] followed by the issue number):

• Add regression test for hb_free_atm for CAM7 above CLUBB

Describe any changes made to build system:

Describe any changes made to the namelist:

List any changes to the defaults for the input datasets (e.g. boundary datasets):

List all files eliminated and why:

List all files added and what they do:

A       cime_config/testdefs/testmods_dirs/cam/outfrq_hb_freeatm_vdiff_derecho/shell_commands
A       cime_config/testdefs/testmods_dirs/cam/outfrq_hb_freeatm_vdiff_derecho/user_nl_cam
  - new testmod

List all existing files that have been modified, and describe the changes:
(Helpful git command: git diff --name-status development...<your_branch_name>)

M       cime_config/testdefs/testlist_cam.xml
  - new testmod

If there are new failures (compared to the test/existing-test-failures.txt file),
have them OK'd by the gatekeeper, note them here, and add them to the file.
If there are baseline differences, include the test and the reason for the
diff. What is the nature of the change? Roundoff?

derecho/intel/aux_sima:

derecho/gnu/aux_sima:

derecho/nvhpc/aux_sima (test is run via Github workflow. Only run the test manually if we need to save new baselines):

If this changes climate describe any run(s) done to evaluate the new
climate in enough detail that it(they) could be reproduced:

CAM-SIMA date used for the baseline comparison tests if different than latest:

[cacraigucar]

Should this use the new variable that Jesse is introducing for the ROOT? I guess it depends on what comes in first, but we need to make sure this one doesn't slip through the cracks if it comes in first

[jimmielin]

Will do! Not sure which will come in first, but I have plenty of test mods I will merge in, so I'll keep this in mind. Thanks for the reminder.