More multisystem messages changes

Description

More changes to handle output in multisystem mode:

• Add option to pass the namespace to the messages_print_var_*.
• Pass and use namespace in messages_check_def.

News snippet

More changes to handle output in multisystem mode.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.