feature #1787 allow NA instead of only integers for hour_interval

[georgemccabe]

This change is nearly identical to #1672

Pull Request Testing

• Describe testing already performed for these changes:
  

Added unit test to ensure correct behavior occurs.

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

Ensure all tests pass

• 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]

• Will this PR result in changes to the test suite? [No]
  

• Please complete this pull request review by 9/9/2022.
  

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[georgemccabe]

All tests passed and the change is very similar to the other PR, so I am merging without review.