HHH-7871 Write cache should not using LOCAL flag

* Flags were not being applied in clustered environments because of
the use of classloader aware cache which was not forwarding them.
HHH-7797 Block "unique" syntax on a column if a constraint can/will be
used
HHH-7797 UniqueDelegate & DefaultUniqueDelegate
HHH-7797 Finished first take on UniqueDelegate and rolled into .cfg and
.mapping
HHH-7797 Initial attempt at using UniqueDelegate within metamodel
HHH-7797 initial test case
HHH-7797 Finished auditing dialects.  Cleanup and javadocs.  Completed
uniqueness test.
HHH-7797 minor refactoring
HHH-7797 Use unique indexes on nullable columns for DB2.  Correctly
handle @UniqueConstraint table annotations on second passes.
HHH-7797 Corrected failing test that was exposed by src changes
HHH-7797 Simplified UniqueKey creation and corrected a couple of
@UniqueConstraint bugs.
Conflicts:
	hibernate-core/src/main/java/org/hibernate/cfg/Configuration.java
HHH-6627 HHH-7752 - Test cases
HHH-7561 - Fix and test ( from Lukasz )
HHH-7437 - Fix and test
(cherry picked from commit bcf73bd32c2af2dc2dcb6e160f4b39e23c532253)
HHH-7866 Avoid redundant log level checking in StandardQueryCache
HHH-7866 Cleanup and added a few more checks
HHH-6643 Criteria doesn't support a chaining of 2 not restrictions (sql
= not not criterion)
HHH-3458 Register postgres random() function as "rand" in PostgresSQLDialect
HHH-6643 Corrected intermittent test failure
HHH-2448 Generate identical column aliases among cluster