Add some kind of Pytest status monitoring endpoint to the SRI web services

[RichardBruskiewich]

At presence, the web services POSTs a testrun request, and uses a session id to get test run results, if and when they are available (this service can "time out" with a null response if the PyTests are not yet completed).

SRI Test runs are likely to be somewhat long-running. It would be helpful to provide an intermediate endpoint action to communicate status updates of the running of the Pytest test run before completion (to allow UI refresh).

This status feedback should also check if the Pytest run worker process is still "alive".

[RichardBruskiewich]

Basic /status endpoint working.