Fix for CORE-1957 Using VARCHAR2 column type fails for Hsqldb running in...

This is a fix for <a href="https://liquibase.jira.com/browse/CORE-1957">CORE-1957, Using VARCHAR2 column type fails for Hsqldb running in oracle syntax mode</a>, that hopefully can be incorporated into the 3.2.1 release. 

Some unit tests have been added and all other tests in liquibase-core are running fine.