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.
For QCDM devices we want most of what MMSerialPort does, but not
the AT command handling stuff since the commands and responses
aren't AT commands nor are they even strings. So convert everything
that MMSerialPort does into a GByteArray, and let MMAtSerialPort
handle the conversion to strings when necessary.
Dan Williams
Aleksander Morgado