This patch changes `ScriptedThreadPlan::GetStopDescription` behavior by
discarding its return value since it is optional in the first place (the
user doesn't need to provide a return value in their implementation).
This patch also addresses the test failures in TestStepScripted
following 9a9ec22 and re-enables the tests that were XFAIL'd previously.
The issue here was that the `Stream*` that's passed to
`ThreadPlanPython::GetDescription` wasn't being passed by reference to
the python method so it was never updated to reflect how the python
method interacted with it.
This patch solves this issue by making a temporary `StreamSP` that will
be passed to the python method by reference, after what we will copy its
content to the caller `Stream` pointer argument.
---------
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>