Introduce BeanManager#getInstances() to ease instance resolution in custom SPI

Right now if you need a bean instance in one of your extension or custom SPI (i.e. instance of Bean A is needed to create Bean B) you have to write something like

Set<Bean<?>> beanSet = beanManager.getBeans(MyClass.class);
Bean<?> bean = beanManager.resolve(beanSet);
MyClass instance = (MyClass) beanManager.getReference(bean, MyClass.class, beanManager.createCreationalContext(bean));

While it can be useful to get thru all this step of type safe resolution, a typical use case is: I need this contextual instance (or these contextual instances) to do conditional action according to its state.

So providing a Bean Manager method returning an Instance<Object> could be a short cut that could help a lot of advanced developers:

beanManager.getInstances().select(MyClass.class).get();