HSEARCH-1560 Moving org.hibernate.search.batchindexing.impl.Executors into org.hibernate.search.util.impl.

Otherwise the batchindexing.impl would need to be exported for ORM which wold create another split package. Also, it is a util class anyways.
HSEARCH-1560 Moving batch indexing progress monitor impl to orm module.
HSEARCH-1556 Introducing maven-bundle-plugin and configure it for the deployable artifacts