test result reporter should not depend on helix-scripts

Currently, HelixSDK injects test reporter to the test runs that will report the test results. However, that currently use Python's propriety Pickle format to serialize test results and it has strong dependency on Helix scripts.
This creates portability hurtle for cases when the scripts are not available. For short term future that may be:
- docker scenarios where we do not need Helix and it's dependencies inside of the container
- HelixClient written in any other language

And there is really no specific reason why Pickle needs to be used as well it creates strong binding for two code bases that does not need to exist at all.

It would be nice to get to some open standard like JSON where there is no strong dependency on various components and the test results can be produced and consumed in any language.