Feature #2690 tmp_files Contributor's Guide

[JohnHalleyGotway]

Expected Differences

Note that this PR is mainly for documentation changes. It describes MET's use of temporary files in the Contributor's Guide and adds relevant links between the User's Guide and Contributor's Guide. At the MET development meeting on 9/28/23, we'll discuss whether or not additional GitHub issues are warranted to refine MET's use of temporary files.

This PR also:

• Removes the unused reference to tmp_dir from regrid_data_plane
• Removes the unused tmp_dir option from the plot_point_obs configuration file/code

Note that I added a Contributor's Guide/dev_details directory rather than just a single dev_details.rst file. I anticipate that we'll want to add many development details, and it'll be convenient to organize the content across multiple .rst files rather than putting it all in one for the entire chapter.

• Do these changes introduce new tools, command line arguments, or configuration file options? [No]
  
  If yes, please describe:
  

• Do these changes modify the structure of existing or add new output data types (e.g. statistic line types or NetCDF variables)? [No]
  
  If yes, please describe:
  

Pull Request Testing

• Describe testing already performed for these changes:
  
  Rendered and reviewed docs locally.

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  
  Please review the proposed doc changes at https://met--2693.org.readthedocs.build/en/2693/

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes]

• Do these changes include sufficient testing updates? [Yes]
  None needed.

• Will this PR result in changes to the test suite? [No]
  
  If yes, describe the new output and/or changes to the existing output:
  
  No, although GHA testing workflow may continue to flag diffs related to PBL heights computed by PB2NC.

• Please complete this pull request review by [Fri 9/29/23].
  

Pull Request Checklist

See the METplus Workflow for details.

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[jprestop]

I have reviewed the documentation changes and have ensured that all tests passed (noting that the failing check under Check for Differences in unrelated). I approve this request. Thank you for your work on this task.