Enable KVM for nested virtualization

[onomatopellan]

Since insider build 19619 user can enable nested virtualization in WSL2 but kernel needs to have KVM enabled for Intel and AMD.

To enable nested virtualization add to the .wslconfig file

[wsl2]
nestedVirtualization=true

$ sudo kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be used

[nathanchance]

Sure, done in v32: 41399ba