Add benchmark for measuring performance impact on moving sandbox across thread

[ludfjig]

KVM docs claim:

vcpu ioctls should be issued from the same thread that was used to create the vcpu, except for asynchronous vcpu ioctl that are marked as such in the documentation. Otherwise, the first ioctl after switching threads could see a performance impact.

It would be beneficial to measure this overhead, as well as overhead on MSHV