ISPN-3777 ThreadLocal in AbstractInvocationContextContainer is leaking instances of LocalTxInvocationContext

https://issues.jboss.org/browse/ISPN-3777

* InvocationContextInterceptor now sets the InvocationContext thread-local
* Batching mode now also uses InvocationContextInterceptor, so there is
  only one place where the thread local is set/removed.
* InvocationContextFactory was extracted from InvocationContextContainer
* The thread-local is not set when the classloader is not needed, or when
  the call classloader (either from AdvancedCache.with(ClassLoader) or from
  the thread's context classloader) is the same as the configured
  classloader (by default, the context classloader of the thread that
  created the GlobalConfiguration).
* DefaultContextClassResolver now prefers the classloader in the
  configuration to the current thread's context classloader (but if they
  are different, the context classloader was already set in the
  InvocationContext and returned by EmbeddedContextClassResolver).