Fix mass-assignment security incompatibility

[#56005352]

metaploit_data_models could not use
'Metasploit::Model::Module::Ancestor' shared example because the
mass-assignment security wouldn't allow new with parent_path or
real_path, so make real_path accessible (since it can be used
legitimately to derive module_type and reference_name now) and set
real_path and parent_path on instance instead of passing to new in
failing context.