rb9704 drives a 9704 on USB and the Cloudloop account behind it, moved
from WII6's host/rockblock with its project names taken out. rb9704-fake
speaks JSPR on a pty or a serial port: everything the library asks, MO in
segments with the CRC checked, MT, signal, provisioning, refusals and
failures on command.
The tests run against the fake at every level: the fake itself, the
command line, Ground Control's Python binding, the shell sample on
native_sim, and the sample on a board (test_zephyr.py, one suite through
two consoles). test_real.py makes free checks against a real modem.
