KVM: VMX: Introduce test mode related to EPT violation VE

To support TDX, KVM is enhanced to operate with #VE.  For TDX, KVM uses the
suppress #VE bit in EPT entries selectively, in order to be able to trap
non-present conditions.  However, #VE isn't used for VMX and it's a bug
if it happens.  To be defensive and test that VMX case isn't broken
introduce an option ept_violation_ve_test and when it's set, BUG the vm.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Message-Id: <d6db6ba836605c0412e166359ba5c46a63c22f86.1705965635.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>