BeanAttributesFactory should ignore illegal bean types

Currently ExternalBeanAttributesFactory throws DefinitionException whereas BeanAttributesFactory does nothing and adds an illegal type in the set of bean types. As a result if an extension wraps BeanAttributes produced by BeanAttributesFactory for a bean with an illegal type, a DefinitionException is thrown.

See also CDI-495 and https://issues.apache.org/jira/browse/DELTASPIKE-817.