Support --show-progress for s5cmd run

[fedorov]

First of all, thank you for creating and maintaining s5cmd - it is an amazing tool!

In the Imaging Data Commons project are developing publicly available cloud-based environment hosting large amount of publicly available cancer imaging data in GCP and AWS, and have been recommending s5cmd to our users for data download for quite some time now.

The nature of our data is such that when users download the files, they need to copy from several bucket folders using manifests and s5cmd run. While the features added in #590 are useful, in our use case scenario, cp --show-progress is not particularly helpful, since it is impossible to track the overall progress of downloading the content defined by the manifest. It would be quite helpful if --show-progress worked with s5cmd run so that the overall progress could be tracked.