paths are somewhat trivial to exploit. instead resolve them to the
actual block device names under /dev/ and pass that into the privileged
helper. the helper then only needs to verify that $name is in fact a
block device under /dev/.
since unprivileged processes cannot create files in /dev/ directly, let
alone block devices, this should give us a very reliable way of
preventing abuse.

these files no longer contain in-cpp qobjects so the files don't need
mocing

only was disabled because the helper wasn't working and I needed in-proc
debugging to figure out why

the exit code of smartctl actually has meaning and we'll likely want to
deal with it to construct more pertinent error messages I think.

although, the code is apparently also reflected in the json so perhaps
passing it along on its own isn't all that meaningful