[WFLY-3846] JMS resources allows duplicate JNDI entries

* use noDuplicateElements ListValidator for attribute definitions
  representing JNDI Entries.

JIRA: https://issues.jboss.org/browse/WFLY-3846
Merge pull request #6699 from jmesnil/WFLY-3846_duplicate_JNDI_entries

[WFLY-3846] JMS resources allows duplicate JNDI entries