Classify ARM version rather than use runner_label
https://github.com/FEX-Emu/FEX/blob/4449b604597a6b23699a9cf18ec75761b053e078/unittests/ASM/CMakeLists.txt#L68

This line in the ASM cmake test uses runner_label directly.
This is kind of annoying when running unit tests locally and haven't set a runner label.
End up seeing "failing" tests but these are just disabled on some platforms.

Instead we should classify the host CPU and choose the file directly.
The `InstallFEX.py` script has a way to classify CPU features to minimum versions that we can reuse. https://github.com/FEX-Emu/FEX/blob/main/Scripts/InstallFEX.py#L98