Feature 2830 sonarqube enum

[hsoh-u]

Expected Differences

The same functionalities but changed the code enum to enum class.

• added enum_as_int.hpp in order to print out enum class as integer

• The header files which are input of enum_to_string are not updated

• The header files which are defined at *.yy are not updated

• The header files which enum variables do the adding/subtracting/increasing/decreasing operations.

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

• [x] 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

• [x] Describe testing already performed for these changes:
  

Unittest

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

N/A

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

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

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

• [x] Will this PR result in changes to existing METplus Use Cases? [No]
  If yes, create a new Update Truth METplus issue to describe them.

• [x] Do these changes introduce new SonarQube findings? [Yes or No]
  If yes, please describe:

It may increase the findings because other rules were not applied at the modified codes.

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

Pull Request Checklist

See the METplus Workflow for details.

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[hsoh-u]

Not sure why duplication was increased by changing enum to enum class. The most new code smells are actually the existing ones, for example, case(xxx) as redundant parentheses. The same lines were changed during enum class but I did not correct them to focus enum class issue.