Show progress bar on scanning

[dineshba]

Initial attempt to show the progress bar.

Current approach:
total := len(currentAdditions) * len(dc.detectors)
After checking one addition with one detector, we will increase the count

[dineshba]

This will be applicable for pre-push and pre-commit hooks also. Should we disable for it ? @svishwanath-tw @harinee

[svishwanath-tw]

@dineshba : On dev machines, it will be informative to have. Only worry is what will happen on CI, will it break/distort the output ?

[dineshba]

I will just print the progress in stderr stream. Should not create any issues in the CI.