Support concept auto-complete field in forms

We need to add support for an auto-complete concept field in json forms. Look up the json forms spec to see how such a field should be defined in json (or ask on talk.openmrs.org).

When the user starts to type, he should see suggestions for matching concepts same as in the web browser version of such a widget e.g. the diagnosis field in the visit note form.

The search should use REST query if online and locally downloaded concepts (see AC-385) if offline.

Create a visit note form for mobile to prove the functionality is working.