ice_history: refactor CMIP history variables

[phil-blain]

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PR checklist

• [X] Short (1 sentence) summary of your PR: refactor the CMIP history code by adding two new fields to our ice_hist_field type.
• [X] Developer(s): me
• [X] Suggest PR reviewers from list in the column to the right.
• [X] Please copy the PR test results link or provide a summary of testing completed below.
  • Base suite is bit for bit (we only check restarts, and this PR modifies the ice_history code).
  • I ran two one-month cases with f_CMIP= 'm' and verified that the history outputs are bit for bit between the two runs, if we remove the history global NetCDF attribute (ncatted -O -h -a history,global,d,, ${test_file})
• How much do the PR code changes differ from the unmodified code?
  • [X] bit for bit
  • [ ] different at roundoff level
  • [ ] more substantial
• Does this PR create or have dependencies on Icepack or any other models?
  • [ ] Yes
  • [X] No
• Does this PR update the Icepack submodule? If so, the Icepack submodule must point to a hash on Icepack's main branch.
  • [ ] Yes
  • [X] No
• Does this PR add any new test cases?
  • [ ] Yes
  • [X] No
• Is the documentation being updated? ("Documentation" includes information on the wiki or in the .rst files from doc/source/, which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/. A test build of the technical docs will be performed as part of the PR testing.)
  • [ ] Yes
  • [X] No, does the documentation need to be updated at a later time?
    • [ ] Yes
    • [X] No
• [X] Please provide any additional information or relevant details below:

I'm working on modifying the history code to write outputs using the correct mask for each variables, instead of hardcoding the use of the tmask as is currently done. In doing so I noticed several things that could be improved in that code and thus refactored it. This is the first of two such refactoring PRs.

Details are in each commit message.

[apcraig]

@dabail10, please have a look if you get a chance and make sure you're happy with this update.

[apcraig]

I ran a full test suite on cheyenne and all the tests pass including regression. This includes the io_suite which tests several features in the history files.