Display progress of NTFS file system specific copy operation (#762366)

Copying of ntfs is performed using ntfsclone, which writes progress
indication to standard output like this:

    # ntfsclone -f /dev/sdb2 /dev/sdb1 2> /dev/null
    NTFS volume version: 3.1
    Cluster size       : 4096 bytes
    Current volume size: 21474832384 bytes (21475 MB)
    Current device size: 21474836480 bytes (21475 MB)
    Scanning volume ...
    100.00 percent completed
    Accounting clusters ...
    Space in use       : 1832 MB (8.5%)
    Cloning NTFS ...
    100.00 percent completed
    Syncing ...

Add ntfsclone progress tracker for ntfsclone command.  Deliberately
doesn't stop the progress bar.  See comment in ntfs::clone_progress()
for the explanation.

Bug 762366 - Add progress bar to NTFS file system specific copy method