kvm-unit-tests: VMX: Add test cases for I/O bitmaps

Add test cases for I/O bitmaps, including corner cases.

Test includes: pass & trap, in & out, different I/O width, low & high
I/O bitmap, partial I/O pass, overrun (inl 0xFFFF).

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>