Allow Dialect version to be specified separately from the dialect class name

Description

We need to be able to specify the dialect version by using the environment settings JAKARTA_HBM2DDL_DB_VERSION, JAKARTA_HBM2DDL_DB_MAJOR_VERSION, JAKARTA_HBM2DDL_DB_MINOR_VERSION. Right now, if the version is specified like this, it is not taken into account.

This would allow replacing something such as

cfg.setProperty( AvailableSettings.DIALECT, Oracle10gDialect.class.getName() );

with

cfg.setProperty( AvailableSettings.DIALECT, OracleDialect.class.getName() );
cfg.setProperty( AvailableSettings.JAKARTA_HBM2DDL_DB_MAJOR_VERSION, "10" );

NB: once the above is implemented, tests that used these deprecated Dialects, should take special care in assuring that they actually get the requested dialect. (e.g. BatchVersionedDataConfigTest.testBatchVersionedDataForOracle10gDialect() may pass, even with a version different from the one specified )