feat: added `--missing` flag to list and remove subcommands#1056

wpk-nist-gov wants to merge 4 commits intojupyter:mainjupyter/jupyter_client:mainfrom

wpk-nist-gov:feature/list-remove-missing-kernelswpk-nist-gov/jupyter_client:feature/list-remove-missing-kernelsCopy head branch name to clipboard