progress: Add a new abstraction to indicate progress

progress: Add a new abstraction to indicate progress

The pakfire library has a progressbar object which is complicated to
handle when functions are called from Python, etc.

This new abstraction allows easy handling of progress inside the library
and other applications can hook into it and show the desired status in
whatever way they like.

This patch also implements a classic progressbar in the CLI utils.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>