Make all error codes containerd-compatible

While we want to make firecracker-containerd mostly containerd-compatible, there were incompatibilities like #457.

Finding and fixing incompatibilities is one. Building a mechanism to prevent incompatibilities is another one, which could be useful for other shims.

Start by reviewing incompatibility issue #457 and locating the existing error-code handling in the repository. Determine the containerd-compatible error-code requirements and how a mechanism could prevent future shim incompatibilities. Done means the relevant error codes are compatible and regressions can be detected.

Written by the indexing model from the issue text.