Move billing to left of shipping in order_details

As discussed in https://github.com/spree/spree/issues/4438

Fixes #4438
Fixes #4443
Use try_spree_current_user instead of spree_current_user

Help us with backend build where spree_curent_user is not available by
default
Fixed taxon_preview helper to work properly with postgresql ordering. Fixes #4382