Pass the device's hardware IDs through modem creation and use them
when calculating the device's identifier. Add a bunch of testcases
for real hardware to ensure we don't break the device ID in the
future unless we really want to.
Instead of returning an unhelpful error when there isn't a second
AT port (which there never will be for Novatel CDMA devices) we should
let the superclass handle the request.
Some Novatel devices reply with the normal units to +CSQ and it
doesn't look quite like the +CSQ reply is in dBm either; so
use the custom Novatel command for RSSI.
Allow plugins to perform asynchronous port detection, and to defer port detection
until later. This moves the prober bits into MMPluginBase so that all plugins
can take adavantage of it only when needed; the probing is not done at udev time.
Furthermore, plugins like Novatel can flip the secondary ports over the AT mode
through deferred detection, by deferring the secondary ports until the main port
has been detected and AT$NWDMAT has been sent.
This commit also finishes the port of the rest of the plugins (except mbm) over
to the new port detection methods and plugin API.
