Provide either progress or ETA info when running a pipeline

[pombredanne]

Some steps doing heavy lifting (such as file-level license or copyright detection) can take a good amount of time and it can be frustrating not to have much more feedback than a given step is started.
For instance the https://github.com/nexB/scancode.io/blob/e574fa9e815c763ac5025f540dfc05d61122d23e/scanpipe/pipelines/scan_codebase.py#L44 step will get us only a Step [run_scancode] starting...
It would be great to have a way to get some progress information. I reckon that the main project web page can be refreshed by hand (F5) and we can see some progress based on the counters and graphics being updated, but this is indirect.

Instead it would be great to get either or both of:

1. some progress bar of sorts displayed on a project page or on the projects lists
2. some indication of ETA left for the current step (and that part is super hard to get right but some indication would go a long way)

[tdruez]

We do have logging for the scancode direct API calls pipes: https://github.com/nexB/scancode.io/blob/main/scanpipe/pipes/scancode.py#L204

We are missing those when calling the toolkit cli through a subprocess.
Let's see if we can stream the progress output from the toolkit for those calls.

[tdruez]

some indication of ETA left for the current step (and that part is super hard to get right but some indication would go a long way)

@pombredanne does the scancode cli provide any of those ETA indication?