cellular: pseudomodem: Support CDMA without activation.

Pseudo modem manager now supports the
org.freedesktop.ModemManager1.Modem.ModemCdma interface, except it
doesn't implement ActivateAutomatic/ActivateManual.

Also fixed a few minor issues, such as bearer initialization and state
machine clean up.

BUG=chromium:219160
CQ-DEPEND=I1b1d78909287e21eb3fbe462869097809d004a1c
TEST=Run "pseudomodem.py -f CDMA". Shill should pick up the CDMA network.
Perform Enable/Disable/Connect/Disconnect in various orders and make
sure that they succeed (the UI and mmcli should show the correct values
for properties). Also verify that Connect/Disconnect operations
correctly update bearer properties using mmcli.

Change-Id: I1bdc0658f858d81215775880ac6045700609d983
Reviewed-on: https://gerrit.chromium.org/gerrit/50090
Commit-Queue: Arman Uguray <armansito@chromium.org>
Reviewed-by: Arman Uguray <armansito@chromium.org>
Tested-by: Arman Uguray <armansito@chromium.org>
10 files changed