Replaced obsolete preprocessor check for simulator/device in C code.
Architecture can no longer be used to determine this with Apple Silicon.
The new code uses `TARGET_OS_SIMULATOR` from `TargetConditionals.h`.
We have some mono libs which can only be used in devide builds.
We were adding them as static libs. Previously it was only causing
warnings because missing arch for the simulator, but now this
is treated as an error.
To fix this we turn them into xcframeworks with dummy static libs
for the simulator and the actual ones for devices.
