Improve the simple console output

[julienw]

When running molotov in a docker container, we have to use the simple console output, but it's not as good as the normal output. Especially we don't see the successes and failures until the end, and that's when running --single-run. When running with --sizing I had to kill the docker container and then I couldn't see any very useful output. Sometimes Ctrl-C works, and then we see the success/failures output.

All we see is a succession of:

[W:5] Ran 10 scenarios
[W:37] Setting up session
[W:37] Running scenarios
[W:38] Setting up session
[W:38] Running scenarios
[W:39] Setting up session
[W:39] Running scenarios

The progress can be followed with Ran 10 scenarios output, but that's not good enough.
It would be good to see regularly a progress of success/failures accross all workers.

Thanks!

[tarekziade]

Try using the new session.print API: https://github.com/tarekziade/molotov/blob/main/molotov/tests/example10.py#L16

Beware that this can end up generating a lot of output, unless you use a mod againstcontext.step for example to print out every n run