feat: support for file headers

[kevgo]

This enables Ory CLI to add headers to source code files in various ways. I decided to build (vs buy) this because that was needed for feature (2) anyways, and I could reuse the functionality to add headers to build a solution for (1) that is custom-tailored to our unique setup.

This PR adds two main capabilities to Ory CLI's dev tooling:

1. add license headers to all files in a folder (implements https://github.com/ory-corp/general/issues/602)

   • call like this: cli dev headers license .
   • adds a license header to all files that can contain comments
   • does not add license headers to .md files
   • the license header text is baked into the tool for now since it should be always the same
   • preview of how the result looks like: docs: standardize license headers hydra#3216

2. add link to original file in ory/meta while replicating from ory/meta to all Ory repos (implements idea: add header to file copies that mentions they are auto-generated and links to the original meta#149)

   • call like this: cli dev headers cp [-r] <source> <destination>
   • behaves exactly similar to cp -r around which files are copied (if not that's a bug in this tool)
   • for each file it copies, it adds a header to the new file pointing to the original file on GitHub
   • this is currently hard-coded to ory/meta since that's the only source of file replication I am aware of right now
   • preview of how the result looks like: DEMO: example header for replicated file hydra#3217

This is an alpha release. Fine-tuning is expected as this is being used more widely.

Related Issue or Design Document

ory/meta#149 and https://github.com/ory-corp/general/issues/602

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 green light (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 necessary documentation within the code base (if
  appropriate).

[aeneasr]

Awesome, let's give this a spin! :)