Legacy compatibility option for executing queries in non-JTA threads

Introduce wildfly.jpa.skipquerydetach extension that allows queries obtained in non-jta thread from container managed entity manager, to not be detached from the entity manager until the entity manager is closed.

The wildfly.jpa.skipquerydetach extension is disabled by default (false), meaning that query results are detached from persistence context when obtained. wildfly.jpa.skipquerydetach can be set to true, for JBoss AS 5/6 compatibility, which defers the detaching of query results until the entity manager is actually closed. This should of been part of WFLY-3674 but was overlooked.

The original goal of WFLY-3674 was to introduce compatibility with earlier JBoss application server versions (5.0/6.0), via an extension for non-JTA transaction scoped entity managers that allows the persistence context to last until the entity manager is closed. However, the WFLY-3674 introduced extension jboss.as.jpa.deferdetach, neglected to update our query execution handling to (if WFLY-3674 introduced extension was enabled) defer detaching of the persistence context.

WFLY-12674 introduces the wildfly.jpa.skipquerydetach, that if set to true, will defer the detaching (clearing) of the persistence context until the entity manager is closed.

To enable the extension, applications should now set both jboss.as.jpa.deferdetach + wildfly.jpa.skipquerydetach to true. Although they may also set one to true but not the other.

Add tests to WildFly testsuite, that verifies that expected behaviour is observed when the feature is enabled and disabled.

pull#12713 already includes documention via docs/src/main/asciidoc/_developer-guide/JPA_Reference_Guide.adoc.

JPA Skipquerydetach extension added for execution of JPA queries in non-JTA threads for legacy compatibility.