Previously, we use CreateConfig's Command to populate container
Command (which is used as CMD for Inspect and Commit).
Unfortunately, CreateConfig's Command is the container's full
command, including a prepend of Entrypoint - so we duplicate
Entrypoint for images that include it.
Maintain a separate UserCommand in CreateConfig that does not
include the entrypoint, and use that instead.
Fixes#3708
Signed-off-by: Matthew Heon <matthew.heon@pm.me>
28b545d04c