Add support for Organization Secrets API

[chtzvt]

This pull request implements support for Organization Secrets.

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Before the change?

• Octokit did not support the Organization Secrets API, so I had to monkeypatch it in.

After the change?

• Octokit now has support for Organization Secrets.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

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This pull request is a draft. I still need to generate cassettes to finish writing tests.

[kfcampbell]

I've marked the PR as a draft and approved the builds. Please ignore the failing Issue/PR response CI; we have an integration without the proper permissions on some repositories.

[github-actions]

👋 Hey Friends, this pull request has been automatically marked as stale because it has no recent activity. It will be closed if no further activity occurs. Please add the Status: Pinned label if you feel that this issue needs to remain open/active. Thank you for your contributions and help in keeping things tidy!