chore: improve header command names

[kevgo]

Improves names of the header subcommands.

BREAKING CHANGES: 
This patch changes the behavior of existing CLI commands that are used internally. 
Please replace "ory dev headers license" with "ory dev headers copyright" 
when updating to the next version of Ory CLI.

Checklist

• I have read the contributing guidelines
  and signed the CLA.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got approval (please contact
  security@ory.sh) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added the necessary documentation within the code base (if
  appropriate).

[kevgo]

@jonas-jonas @alnr FYI I'm cleaning up some technical drift that occurred while I developed this feature, so that the naming makes sense when you take this over. I'll alo update the usage of this command across all repos.