How to create a new SQL command

Using drop table as example:

• create a new Red::AST::DropTable
• create a .^drop-table method on MetamodelX::Red::Model (like the .^create-table method)
• add a multi method translate(Red::AST::DropTable $_, $context) on Red::Driver::CommonSQL
• if is there any supported database where the SQL for drop a table is different from the CommonSQL one, add a multi method translate(Red::AST::DropTable $_, $context) on that driver