Feature: support to push only fast-forward changes into protected branches

[visit1985]

We are trying to implement protected branches in CodeCommit. Protected branches do not allow to alter the commit history by force-pushing non-fast-forward changes. The codecommit:MergePullRequestByFastForward IAM action applies to the console and API only, while all Git client write operations are permitted via the codecommit:GitPush IAM action. Since codecommit:GitPush lacks a condition keys to limit clients to fast-forward pushes only, there is no way to protect a branch without denying all Git client write access for it and use solely API actions to manage this branch instead. There are certain Git-Workflows and automations that do not rely on concepts like merge/pull requests and thus do not require API/console access, which are blocked by this.

I would like to request an IAM condition key to restrict Git clients to fast-forward pushes for protected branches.

I'm aware that this is a service side feature request, but the support directed me here anyway. Please review Case ID 171696449600152 for this.