support -foreground option in dvresuce, similar to avfctl

[dericed]

I'm trying to find the last pieces of avfctl that we need in dvrescue and one is the foreground option.

If I want to repack the tape (fast forward all the way, wait til the end of the tape, and then rewind all the way) in avfctl I could do this:
avfctl -cmd ff -foreground; avfctl -cmd rew;
In dvrescue, I have to send the ff command, and then keep checking via the status to see if its done and then rewind it.