Simplify Prototype Scoped Bean Definition for BPMN Activities

[hhund]

To simplify the definition of prototype scoped beans for BPMN activity services like ServiceTask, MessageIntermediateThrowEvent, ExecutionListener, etc. in spring @Configuration classes, we should create a BeanDefinitionRegistryPostProcessor that automatically creates beans based on specified class objects.

The processor should allow automatic dependency injection of other beans via constructor arguments.

This is a backfill issue for the change-log as this was mostly implemented via #290