IncrementalRuleCodegen should generate all related rules when one DRL file is changed

At the moment hot reload of Kogito extesnsion for Quarkus only works when modifying an existing rule. It should also work when new rules (or entire drl files) are added or removed.

Solution: we allow to codegen all the related files when compilation is re-triggered. The solution entails reworking IncrementalRuleCodegen – with the occasion, we will be able to refactor so that this class is used everywhere rule codegen is done (including maven plugin and tests)