Add a Test for RadioBandMode to Ensure Auto Mode

The radio band mode is perilous because depending
on the setting and the detected locale, other
settings may be disabled. That can leave the modem
in a soft-brick state. Thus, BandMode = 0 = AUTOMATIC
should always be supported so that the modem can
update and select a band mode of its choosing.

Bug: 28124606
Test: vts radio - getAvailableBandModes
Merged-In: I1f25d9125ef06d290e3a89b5d2162c6bfe939eba
Change-Id: I1f25d9125ef06d290e3a89b5d2162c6bfe939eba
(cherry picked from commit c9e391801ba5ccd24b41481b26c2861b71ef03d0)