iso_extract: Reimplement using 7zip (not requiring root) (#24937)

* Reimplement iso_extract using 7zip (not requiring root)

So one of the drawbacks of the original implementation is that it required root for mounting/unmount the ISO image.
This is now no longer needed as we use 7zip for extracting files from the ISO.

* Fall back to using mount/umount if 7zip not found

As discussed with others.

Also improved integration tests.
This commit is contained in:
Dag Wieers 2017-08-04 20:38:42 +02:00 committed by jctanner
commit 25e67d804c
8 changed files with 307 additions and 60 deletions