MdePkg/Library/UnitTestHostBaseLib: Add missing services

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2862



Add ReadMmx()/WriteMmx() services
Add MemoryFence() service

Cc: Liming Gao <liming.gao@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>