[COMPLIANCE] Add copywrite config, GH workflow and headers

[austinvalle]

Closes #656

This PR introduces:

• make generate command that will auto-generate all copyright headers for this repo (hooks into go generate)
• GH workflow that will error if copyright headers aren't present
• Addition to the CONTRIBUTING.md on how to run license autogenerating commands

[bflad]

One minor addition to the workflow, but otherwise looks great 🚀

[bflad]

I think this is okay to merge in since the digital team should be adding this to their management and we can flag it during review if the header is trying to be removed.

[github-actions]

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