Confusing message after an attempt to delete non-existing object (codeset, workflow...)

[jsuchome]

When invalid identifier is given to delete command, delete operation does not fail (which might be correct), however the CLI reports e.g.

Codeset %s successfully deleted

(same for workflows and probably other objects)

which is simply untrue and may lead to incorrect ideas about the state of fuseml.

Looks like we need to pass specific return codes from the backend to CLI which are not necessary error so that we can react accordingly.