"checkout" options

[lteague]

github-actions-s3-deploy allowed users to specify "checkout-repo = false" to allow projects to re-use the build created from another step.

Bring this functionality back. The specific functionality this enables is the option to use LFS checkouts by supplying the option "lfs: true" to actions/checkout.

In addition to supporting checkout-repo=false, supply an option to enable LFS support directly via a "checkout-lfs" input that defaults to false.