[RFE] Add validation of wireserver statuses and substatuses

## Current situation
Testinit does not currently look into any aspects of the POST request payload that Azure-init sends. The service simply responds with a 200 success.

## Impact
This ensures that Azure-init continues effectively reporting ready to the Wireserver.

## Ideal future situation
Ideally, our system matches the real WireServer's validation of status and substatus, and when these do not match, returns an error.

## Additional information