Add pmb:cross-native/!tracedeps to applicable firmware packages and
secure both with a test.
This sets the pmb:cross-native and !tracedeps options on all firmware-*
packages that are compatible with the native compilation method. A unit
test ensures the presence of both options while maintaining a list of
exempted packages.
Fixes: #718
[ci:ignore-count] [ci:skip-vercheck] [ci:skip-build]
On top of the firmware we already have, we also need device-specific
modem firmware. Use script from firmware-motorola-potter(credit goes to
Sireesh Kodali). Also imitate the logic in firmware-motorola-potter.
