OPENDJ-1631 CR-6864 Migrate server to SDK syntaxes Replace server AttributeSyntax<T> class by SDK Syntax class Update server syntaxes (still used, but for config only) to use SDK syntaxes under the cover

OPENDJ-1777 Move test source directory to src/test/java Move all test code from tests/unit-tests-testng/src/server directory to maven standard test source directory src/test/java Update pom.xml accordingly