Add API to obtain current injection point from Bean#create

There's currently not a clear way on how to obtain the current injection point (if any) from Bean<T>#create.

A previously somewhat accepted way (though not specified) was:

  Bean<? extends Object> bean = beanManager.resolve(beanManager.getBeans(InjectionPoint.class));
  InjectionPoint injectionPoint = (InjectionPoint) beanManager.getReference(bean, InjectionPoint.class, creationalContext);

This however broke in some version of Weld.

Since getting the injection point is an often used feature in producers, I'd like to propose to introduce an easy API for this, so Bean<T> implementations can use this just as easily. E.g. something like: BeanManager#getCurrentInjectionPoint().

Also see: http://cdi-development-mailing-list.1064426.n5.nabble.com/Getting-injection-point-from-Bean-create-td5710505i20.html