Refactor model to cater to richer display of non-primitive data types

[1t5j0y]

With the introduction of subject and location concept data types, there is need to update the model to allow for richer display of these data types on the clients.

Tech tasks:

• Model: Introduce a Displayable type which includes both the text to be displayed as well as a backing entity object that can be accessed by the respective clients to generate the richer display.
• Model: Add plumbing in order to fetch the backing entity objects as required based on the data type.
• Server: Update Server to return the required entity objects against observations.
• DEA: Update Data Entry App to use the new displayable class
• Android Client: Update Android client to use the new displayable type.

Acceptance criteria: All observations in Registration, Enrolment, Encounter, Program encounter should continue to be shown as before. Observations with concepts data type Subject will be linked to the particular subject.

[1t5j0y]

APK Available at https://s3.ap-south-1.amazonaws.com/samanvay/openchs/staging-apks/staging-5e0a7-2020-10-28-14-25-58.apk

[hithacker]

Test scenarios:

• [x] Test with one of the implementations with old rules and decisions and inheriting from 1. tested on sewa rural using user sr-staging
• [x] Test with one of the implementations with new rules and decisions
• [x] Test all type of concepts