Order should be form recordable

1. Background

Further and further entities than obs are candidates to be recorded through forms via ad-hoc form controls. This requires to provide a way to track their form field namespace and path in order to provide a way to reconstruct the form display from their data as it was recorded in the first place.

2. Description

This has already been added to Condition via TRUNK-5862.
Order should offer something similar through implementing a new common FormRecordable interface.

 
(Originally requested by Dimitri R here: https://talk.openmrs.org/t/introducing-a-platform-team-for-openmrs/33828/19)