Feature 2697 pb2nc temp file

[hsoh-u]

Expected Differences

pb2nc.cc and tmp_file_use.rst are for this issue.

The other files are for SonarQube findings (mostly code smells).

• move down the namespace declaration after include statements

• replace 0 to nullptr

• removed unused variables

• removed always true condition

• Changed the same variable name at the lower scope (shadowed variable)

• 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:
  

Ran the unit tests and compared the output with nightly build
The temp files are deleted by MET. I checked the temporary files by modifying pb2nc.cc temporarily.

The feature branch build is available at /d1/personal/hsoh/git/pull_request/MET_feature_2697_pb2nc_temp_file.
The unit test output is available at /d1/personal/hsoh/git/pull_request/MET_feature_2697_pb2nc_temp_file/unit_test_output

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  

N/A

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

• Do these changes include sufficient testing updates? [No]

• Will this PR result in changes to the test suite? [No]
  
  If yes, describe the new output and/or changes to the existing output:
  

• Please complete this pull request review by [Fill in date].
  

Pull Request Checklist

See the METplus Workflow for details.

• Review the source issue metadata (required labels, projects, and milestone).
• Complete the PR definition above.
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• Define the PR metadata, as permissions allow.
  Select: Reviewer(s) and Development issue
  Select: Milestone as the version that will include these changes
  Select: Coordinated METplus-X.Y Support project for bugfix releases or MET-X.Y.Z Development project for official releases
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• After the PR is approved, merge your changes. If permissions do not allow this, request that the reviewer do the merge.
• Close the linked issue and delete your feature or bugfix branch from GitHub.

[jprestop]

I reviewed the files that were changed and ensured the tests passed. Thanks for taking the time to move "using namespace std;" in the files you touched. Thanks for all of your work on this task.