The columns in the new table should be specified as name-definition pairs (e.g. 'name' => 'string'),
where name stands for a column name which will be properly quoted by the method, and definition
stands for the column type which can contain an abstract DB type.
The method [[QueryBuilder::getColumnType()]] will be called
to convert the abstract column types to physical ones. For example, string will be converted
as varchar(255), and string not null becomes varchar(255) not null.
If a column is specified with definition only (e.g. 'PRIMARY KEY (name, type)'), it will be directly
inserted into the generated SQL.