Provide available values for dbms attribute of io.jmix.core.metamodel.annotation.Ddl annotation

[Gasloff]

This dbms codes differs from the Liquibase ones. It confuses users.

According to Studio code, here is available options list:

• hsql
• postgres
• mysql
• mssql
• mssql-2005
• mssql-2008
• mssql-2012
• oracle