fix use the IOService or IODeviceTree parser to get the data if remotectl_dumpstate is not available

[cvandeplas]

in init get_case_metadata()
use the IOService or IODeviceTree parser to get the data if remotectl_dumpstate is not available

requires those parsers to exist :-)

[ddurvaux]

IOService implemented in ./parsers/ioservice.py
IODeviceTree implemented in ./parsers/iodevicetree.py

Both relies on IOKit object which are parsed by library ./utils/ioreg_parsers/structure_parser.py

[ddurvaux]

Fixed in commit: b0ad3e1

[ddurvaux]

@cvandeplas for closure