[ethanjli]

This PR resolves #491 by replicating how the Docker CLI displays image pulling progress:

• When pulling images without parallelism, it displays progress information the same way as the Docker CLI, except the progress information is correctly indented
• When pulling images with parallelism, it displays progress information just like in pulling images without parallelism, except if progress information is being displayed for image A and then image B finishes being pulled, the progress completion outputs for image B will be displayed for that image, and then the progress information will return to image A. Otherwise, there is no interleaving of progress information between images.

This PR also bumps github.com/urfave/cli from v4 to v5.