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.

I've built all firmware-* packages locally with a shell script. I also compared the build time: on my machine the build is almost 70% faster after this change.

One notable thing: I exempted firmware-xiaomi-willow because it currently doesn't build due to a dead source link. This should probably be looked into separately.

I kept everything in one commit for simplicity but am happy to script-split this into one commit per package plus a final commit for the test if needed.

Fixes: #718 (closed)