KVM: selftests: Introduce hyperv_features test

The initial implementation of the test only tests that access to Hyper-V
MSRs and hypercalls is in compliance with guest visible CPUID feature bits.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-31-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>