Use BeanManager#resolve instead of iteration in SEArtifactFactory

org.jberet.se.SEArtifactFactory#getBean currently iterates thru the results of beanManager.getBeans(ref), and returns the first element (there should be only 1 element in the results).

We should use javax.enterprise.inject.spi.BeanManager#resolve instead.

resolve method basically does:

• if beans is null or empty, return null;
• if only 1 element, return it;
• if more than 1 element, throw ambiguous deps exception.