Added a new concept of "operator classes" to the SQL operators supported by
SQLAlchemy, represented within the enum :class:`.OperatorClass`. The
purpose of this structure is to provide an extra layer of validation when a
particular kind of SQL operation is used with a particular datatype, to
catch early the use of an operator that does not have any relevance to the
datatype in use; a simple example is an integer or numeric column used with
a "string match" operator.
Fixes: #12736
Change-Id: I44f46d7326aef6847dbf0cf7a325833f8e347da6
Mike Bayer
34740d33ab