Add configuration option to allow ignoring command reply publishing errors

[balenio]

Command reply topics can be ephemeral (e.g. tied to the lifetime of the service instance that published the command). In those cases an error publishing to the reply topic can be final, i.e. not recoverable by NACKing and retrying and would cause the reply message to spin needlessly. This change adds a configuration option in the form of a function callback that allows to inspect the error and optionally ignore it, while keeping the previous behavior (NACK unconditionally) as default.