Abstract_WC_Order_Data_Store_CPT::read() hardcoded its validation against
the 'shop_order' post type. However, custom order types created via the
wc_register_order_type() API can use different post types. For example,
refunds have the post type: 'shop_order_refund'.
This patch changes the Abstract_WC_Order_Data_Store_CPT::read() validation
to check that the post type is any of the registered order types.
This fixes refunds and 3rd party custom order types, like subscriptions.
Justin Shreve
Brent Shepherd
Manos Psychogyiopoulos
Mike Jolley