Make mill/mill.bat launcher scripts fall back to non-native binary when used on unsupported OS/CPU platforms

[lihaoyi]

In particular, we need to make sure that mill.bat ignores the -native suffix when used on Windows/ARM, at least until oracle/graal#9215 is resolved upstream

[lefou]

If we would add support for a -jvm suffix, we could let the launcher autmatically decide which platform to choose, when it finds a pure version (without any platform suffix). Since the user is still able to explicitly use the JVM only.

Edit: Oh, I didn't realized you already proposed exactly that idea as #4415.