feature: Checkout Key Management

[nairb774]

Would there be interest in adding a resource for managing a project's "checkout key"? There looks to be APIs for get, create, and delete.

We would have a use for this when combined with the Github provider to manage distribution of the keys. If this could be interesting, I would be happy to try to pull a PR together.

[ViktorLindgren95]

Would be great, would make handling cross dependencies with deploy keys a lot easier

[kelvintaywl]

hi @nairb774 @ViktorLindgren95

I've recently added support for checkout keys in my Terraform provider for CircleCI, amongst many other resources.
Hopefully, this can help you 🤓