Remove support for device-specific builds?

Device-specific builds were originally implemented for two reasons:

1. Building for a single architecture when we knew which device the app was going to be installed on (for example: there's no reason to build for armv7 if the app will be installed on an arm64 device).
2. Speed up resource compilation a bit by filtering resource compilation to the target device.

However, the first reason is not applicable anymore (arm64 is the only architecture).

The support for device-specific builds also has a few downsides:

1. It complicates our code.
2. It increases the path length of the contents in the bin directory, which can be a problem for Windows (due to MAX_PATH limitations).

So the question remains: is the resource compilation build speed decrease worth it for the downsides?

One option could be to disable it by default + add telemetry, and if nobody complains + telemetry shows nobody turns it back on again, then we can remove it.

CC @emaf @mauroa @dalexsoto