DDL generator: fixes for include and partial indexes

• added creation of an index for attributes of type "Entity" if the attribute has the value allowNull: true and dbExtensions contains a unique index in which the same attribute is the first (example: bpm_Task_ppt.objectID). Usually we do not create a separate index by column in such case, but for MS/PG ddl generator extends unique index from dbExtensions with filter: "attr is not null", so usual index also needed
• fixed partial index re-creation in case there is spaces in filter definition
• ignore order of items in index include while comparing (some databases returns included columns in alphabetic order) This prevents re-creating indexes with non-ordered include in *.meta