Add option to output in json format

[QuirkyMarc]

Some of us want/need dumps in json rather than yaml.

• Add --output-format argument, and validation of the input.
• Refactored output formatting into output_formatting() function that takes requested format and jq filter as parameters.
• Changed destination_resource_name definitions to use appropriate suffix (.yaml vs .json)
• Modified each
  kubectl ... | jq ... | yq ... > ...
  to a new
  kubectl ... | output_formating ... > ...