DATAJPA-631 - ResourceLoader improvements in ClasspathScanningPersistenceUnitPostProcessor.

A custom ResourceLoader configured on ClasspathScanningPersistenceUnitPostProcessor is now propagated to the ClassPathScanningCandidateComponentProvider used for looking up entity classes. We also forward the configured environment so that profile annotations are evaluated as well.

Related issue: DATACMNS-591.
DATAJPA-632 - Fix SimpleJpaQueryUnit test after cleanups in Spring Data Commons.

We now use a JpaQueryMethod instance rather than a mock as isPageQuery() cannot be mocked anymore as it has been made final.

Related issue: DATACMNS-601.