vm: make binfmt emulation configurable

[winterqt]

As ed49fef4ad63ec48055b4b230ecbad00c54f5417 did for Rosetta, this change adds a flag to control whether binfmt emulation is setup.

In the future, I think it'd be interesting to consider making the option's type []string | bool, where true keeps the default behavior of automatically picking the architectures to enable, false disables binfmt setup, and a list will let the user define which architectures to emulate. (I'd be happy to do this here if you'd like, I think it may be the better solution. :))