x86: vmx: Add test for MTF on a guest MOV-to-CR0 that enables PAE

Verify that when L2 guest enables PAE paging and L0 intercept of L2
MOV to CR0 reflects MTF exit to L1, subsequent resume to L2 correctly
preserves PDPTE array specified by L2 CR3.

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Peter Shier <pshier@google.com>
Message-Id: <20200819205633.1393378-1-pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>