### Is your feature request related to a problem? Please describe Not necessarily, just two variations of the feature described in this issue #38. ### Describe the solution you'd like The following setting `rule_activation_mode: many_by_group` allows Arta to be used as a simple process execution engine. But, this flow of control is applied on all the rules of a rule set. The idea is to be able to define the scope of different rule activation modes: at rule group and even rule levels.