Introduce EJB-based transactional tests in the TCF

This commit introduces transactional integration tests executing
against both JUnit and TestNG in the TestContext framework (TCF) using
@TransactionAttribute in EJBs instead of Spring’s @Transactional
annotation.

These tests disprove the claims raised in SPR-6132 by demonstrating that
transaction support in the TCF works as expected when a transactional
EJB method that is configured with TransactionAttribute.REQUIRES_NEW is
invoked. Specifically:

 - The transaction managed by the TCF is suspended while such an EJB
   method is invoked.
 - Any work performed within the new transaction for the EJB method is
   committed after the method invocation completes.
 - The transaction managed by the TCF is resumed and subsequently
   either rolled back or committed as necessary based on the
   configuration of @Rollback and @TransactionConfiguration.

The configuration for the JUnit-based tests is straightforward and self
explanatory; however, the configuration for the TestNG tests is less
intuitive.

In order for the TCF to function properly, the developer must ensure
that test methods within a given TestNG test (whether defined locally,
in a superclass, or somewhere else in the suite) are executed in the
proper order. In a stand-alone test class this is straightforward;
however, in a test class hierarchy (or test suite) with dependent
methods, it is necessary to configure TestNG so that all methods within
an individual test are executed in isolation from test methods in other
tests. This can be achieved by configuring a test class to run in its
own uniquely identified suite (e.g., by annotating each concrete
TestNG-based test class with @Test(suiteName = "< Some Unique Suite
Name >")).

For example, without specifying a unique suite name for the TestNG
tests introduced in this commit, test methods will be executed in the
following (incorrect) order:

 - CommitForRequiredEjbTxDaoTestNGTests.test1InitialState()
 - CommitForRequiresNewEjbTxDaoTestNGTests.test1InitialState()
 - RollbackForRequiresNewEjbTxDaoTestNGTests.test1InitialState()
 - RollbackForRequiredEjbTxDaoTestNGTests.test1InitialState()
 - CommitForRequiredEjbTxDaoTestNGTests.test2IncrementCount1()

The reason for this ordering is that test2IncrementCount1() depends on
test1InitialState(); however, the intention of the developer is that
the tests for an individual test class are independent of those in
other test classes. So by specifying unique suite names for each test
class, the following (correct) ordering is achieved:

 - RollbackForRequiresNewEjbTxDaoTestNGTests.test1InitialState()
 - RollbackForRequiresNewEjbTxDaoTestNGTests.test2IncrementCount1()
 - RollbackForRequiresNewEjbTxDaoTestNGTests.test3IncrementCount2()
 - CommitForRequiredEjbTxDaoTestNGTests.test1InitialState()
 - CommitForRequiredEjbTxDaoTestNGTests.test2IncrementCount1()
 - CommitForRequiredEjbTxDaoTestNGTests.test3IncrementCount2()
 - RollbackForRequiredEjbTxDaoTestNGTests.test1InitialState()
 - RollbackForRequiredEjbTxDaoTestNGTests.test2IncrementCount1()
 - RollbackForRequiredEjbTxDaoTestNGTests.test3IncrementCount2()
 - CommitForRequiresNewEjbTxDaoTestNGTests.test1InitialState()
 - CommitForRequiresNewEjbTxDaoTestNGTests.test2IncrementCount1()
 - CommitForRequiresNewEjbTxDaoTestNGTests.test3IncrementCount2()

See the JIRA issue for more detailed log output.

Furthermore, @DirtiesContext(classMode = ClassMode.AFTER_CLASS) has
been used in both the JUnit and TestNG tests introduced in this commit
in order to ensure that the in-memory database is reinitialized between
each test class.

Issue: SPR-6132