Use core cucumber event bus implementation

[mvz]

Summary

Replace Aruba's own EventBus implementation with the one from cucumber-core. A few extra methods are provided for compatibility with current use of the event bus.

Details

• Only support symbols to specify events
• Base Aruba event bus on the core Cucumber event bus
• Remove obsolete Aruba::EventBus::NameResolver

Motivation and Context

The existing implementation, in particular the resolver, seemed overly complex for how it was used. The core implementation is simpler and using it instead of our own reduces duplication.

How Has This Been Tested?

Specs were run.

Types of changes

• Internal change (refactoring, test improvements, developer experience or update of dependencies)