Stack locking doesn't support Atlantis-style apply before merge workflow

If you’re implementing an apply-before-merge workflow with Spacelift, you quickly notice that multiple open PRs from different people can quickly cause issues from stepping on toes (i.e., PR A apply reverts changes from PR B because A and B are simultaneously testing changes).

An obvious potential solution to this is to use stack locking, but this has some big drawbacks. First, if the stack lock is owned by a pull request ID, then no humans can modify it. Second, if the stack has autodeploy disabled, then no human can confirm an unconfirmed run.

It would be nice if Spacelift offered a variation of stack locking that could support this use case, or shared an opinionated workflow for how to faciliate quick testing of Terraform changes.