Transaction object store type would be better to be set with custom operation

It would be good to have custom operation for switching transaction object store type (currently available standard file system, journal one - hornetq/activemq, jdbc).

Currently there is quite a bit inconsistency when object store type is needed to be set (once you need to your composite operations, other time you can't use them otherwise you get errors).
All this is discussed in jiras WFLY-2623 and WFLY-5126

As result of discussion https://issues.jboss.org/browse/WFLY-2623#comment-13100037 this issue is raised.

It would be much better for user to have single way how to switch the object stores and custom operation could solve this issue.