Allow setting alternative qrexec service to retrieve backup content. The
service API is slightly different than the default one: it will get only
list of files/directories to extract on its stdin, but not backup
location. The latter could be provided as a service argument, or using
other out-of-band mechanism.
This will be useful for paranoid backup restore mode, to take away
control over location/command from sandboxed qvm-backup-restore process.
QubesOS/qubes-issues#5310
Previous commit introduced protection against uncommon (potentially
malicious) compression filters. This breaks restoring backups made with
a custom compression filter. Add an option to override this check, by
naming compression filter to use explicitly.
Most of them are moved from core-admin repository, even if tool is not
implemented yet. Some are generated using skel-manpage.py script.
This way we have complete man pages list, and sphinx will properly
warn/error about inconsistencies.
