Add support for Dependabot and Codespaces secret management

[kamarcum]

Resolves #1594

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Before the change?

• The endpoints for Codespaces secrets and Dependabot secrets weren't supported.
• Actions secrets methods had names like get_secret, which is ambiguous now that there are more secret types.

After the change?

• Now there are 3 flavors of each secret operation, such as get_actions_secret get_codespaces_secret and get_dependabot_secret

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

At the moment, the previous methods such as get_secret are gone. But I suspect we'll be happier if I alias ActionsSecrets to support the old names. I'll update this section if we do that.

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[kfcampbell]

Thank you @kamarcum! I'll get this merged and release a v7.0.0 in the near future.