Fix ShippingMethod select for MySQL 5.7 strict
Fix ShippingMethod select for MySQL 5.7 strict

This was previously failing under MySQL 5.7 because we were grouping by
only shipping_methods.id, but selecting shipping_methods.*.

This commit avoids the issue by moving the group by into a subquery.

pervino/solidus,pervino/solidus,pervino/solidus,pervino/solidus