Create default community health files (CODE_OF_CONDUCT.md, CONTRIBUTING.md, SUPPORT.md) for whole organization

[MattF-NSIDC]

Our codes of conduct (and some other things) are always the same. We can apply org-level defaults by putting certain files in this repo. Read more: https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/creating-a-default-community-health-file

https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/creating-a-default-community-health-file