Move the version-check for pruners to the pruner, which can
return a [ErrNotImplemented] error to indicate they won't
be run with the API version that's used.
This helps separating concerns, and doesn't enforce knowledge
about what's supported by each content-type onto the system
prune command.
[ErrNotImplemented]: https://pkg.go.dev/github.com/docker/docker@v28.3.3+incompatible/errdefs#ErrNotImplemented
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
bf8cb43025