Fix EZP-20848: PDOException when using Field criterion with ezxmltext

This PR fixes issue https://jira.ez.no/browse/EZP-20848

Using Field criterion with non-searchable fields was not handled.

This solves the problem by throwing ```ForbiddenException``` from storage when that is the case. Exception needs to be thrown in storage since Field criterion uses field identifier, which means search is performed on all fields with that identifier. These Fields are loaded and FieldType identifier for them is determined in the storage.

Also ```NotImplementedException``` is thrown when search is performed with Field on which search is not implemented in Legacy Storage, but is otherwise searchable.

Adding search on these fields will be done through followup issues.