Integrate Wrapper for Telemetry Client

[felixnext]

The Application Insights telemetry client provides various exception handling and metric tracking abilities.

It would be great to directly integrate them into FuncTown (thereby allowing to track return types, exceptions and various metrics through App Insights)

Design for this has yet to be done

[felixnext]

Looks like the Python APIs moved to OpenCensus: https://learn.microsoft.com/en-us/azure/azure-monitor/app/opencensus-python

[felixnext]

Basic design: Idea would be to integrate an additional handler

@handle_errors(debug=True, log_all_errors=DEBUG, return_errors=DEBUG)
@metrics(instrumation_key="key", send_basics=True)
def main(req: http.HttpRequest, logger: logging.Logger, **kwargs):
  # ...

  # execute metric
  logger.metric("foobar") 

In the case of send_basics the wrapper should automatically send basic logging information around response codes, failures, etc.

Note that the logger object should also be picked up by handle_errors in #9.

Note: There should be a convention from now on to only pass named parameters from decorators (apart from req), so that the main function can be modified to main(req, **kwargs) without ever breaking compatibility