Implement keyword argument support in METdbLoad.ush.met_db_load.main and allow calling the function from other Python modules

[joelheaps]

Per #385, we have a use case for METdbLoad that involves installing METdataio as a package, importing METdbLoad.ush.met_db_load.main and calling it from our own Python module. However, we had a couple issues when we tried to do that; I won't rehash them here, but essentially this PR attempts to address most of them:

• Modifies met_db_load.main to accept standard keyword arguments, retaining the defaults that argparse currently uses.
• Modifies met_db_load.print_version to use importlib.metadata to lookup the metdataio package version.
• Removes self in the logger call in question. Also instantiates logger as it's not always instantiated when an exception is caught. (I'm not 100% happy with the fix, but maybe it'll inspire someone else. Current implementation won't respect the configured loglevel, for instance.)
• Adds netcdf4 and metcalcpy to requirements.txt
• Updates tests to use keyword arguments when calling met_db_load.main
• Lastly, renames met_db_load.main to use a more descriptive name (met_db_load.load_met_data).

Pull Request Testing

• Describe testing already performed for these changes:
  
  Ran existing test suite using python -m pytest, with a local SQL database running under Docker.

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  
  This shouldn't change any external behavior when calling met_db_load.py, but if their are test suites in other DTCenter applications that import and call met_db_load functions directly, they may need edits now.

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

• Do these changes include sufficient testing updates? [Yes or No]
  
  Yes. Tests were adapted to use keyword arguments to call main() load_met_data()

• Will this PR result in changes to the test suite? [Yes or No]
  If yes, describe the new output and/or changes to the existing output:
  
  Yes, although no significant changes. (No new tests, only argument changes in existing method calls.)

• Do these changes introduce new SonarQube findings? [Yes or No]
  If yes, please describe:
  
  Unsure. Will edit once I figure out how to check.

• Please complete this pull request review by [Fill in date].
  
  None requested.

Pull Request Checklist

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• Add any new Python packages to the METplus Components Python Requirements table.
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• Ensure the PR title matches the feature or bugfix branch name.
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  Select: Milestone as the version that will include these changes
  Select: Coordinated METplus-X.Y Support project for bugfix releases or METdataio-X.Y.Z Development project for official releases
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