Update status field in service request if the service request gets completed or failed

[tejash-jl]

Describe the bug
Service request entity contains a field STATUS. When a service request is created STATUS is set to NEW. But once the service requests get completed or failed the STATUS field is not updated.

To Reproduce
Steps to reproduce the behavior:

1. Create a workflow
2. Trigger service request
3. Get service requests by workflow name
4. STATUS field in the response is always NEW

Expected behavior
STATUS field in service request should portray the current status. Once the service requests get completed/failed it should be updated.

[sivachandran]

The status is not persisted in DB. It is derived from the step statuses every time service request status API(i.e., .../serviceRequest/:serviceRequestId).

A workflow may have hundreds or even thousands of service requests. Computing statuses on-demand for that many service requests inside this API is going to take a lot of time. So, I suggest we don't return status and other finer detail in the API response. If the client is interested, it can call service request status API to get finer detail.

Alternatively, we can compute and persist the service request status as on when its steps are completed. In this way, the status would be readily available. But, this might involve a significant change in the implementation.