OvmfPkg/VmgExitLig: HALT on #VE when access to private memory

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4125



EPT-violation #VE should be always on shared memory, which means the
shared bit of the GuestPA should be set. But in current #VE Handler
it is not checked. When it occurs, stop TD immediately and log out
the error.

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Guorui Yu <ruogui.ygr@alibaba-inc.com>
Tested-by: Guorui Yu <ruogui.ygr@alibaba-inc.com>