Consistent support for JTA 1.1 TransactionSynchronizationRegistry

JtaTransactionManager's configuration options for a TransactionSynchronizationRegistry are now in sync with the options for UserTransaction/TransactionManager. Specifically, there are setTransactionSynchronizationRegistry/getTransactionSynchronizationRegistry methods for programmatic configuration now.  Motivated by Spring's adapting to a Hibernate JtaPlatform, specifically the Hibernate 4.3 changes in that area.

Issue: SPR-10839
Compatibility with Hibernate 4.3

Due to key SPI interfaces such as ConnectionProvider and JtaPlatform changing their package location in Hibernate 4.3, we have to resort to reflection in a few places. Most importantly, the ConfigurableJtaPlatform used by the setJtaTransactionManager method has now been redesigned as a reflective proxy.

Issue: SPR-10839