It would be quite handy to be able to call:
is_cellular_device and is_outdoor_device from platform.lua in the image-customization.lua

Originally posted by @maurerle in #3054 (comment)

This might be handled by one of the following:

1. from the openwrt json source
2. by extracting the list of devices from platform.lua to something more dynamic (like a separate json file)
3. by extracting the two functions into a separate lua file which can also be imported by image-customization-lib

What is the preferred way to tackle this in the future @blocktrron?