SecurityPkg: Add gmock example

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4389

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Chris Johnson <chris.n.johnson@intel.com>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Oliver Smith-Denny <osde@linux.microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

SecurityPkg/Library/SecureBootVariableLib/UnitTest/MockUefiLib.inf

@@ -18,9 +18,9 @@
   INF_VERSION                    = 0x00010005
   BASE_NAME                      = MockUefiLib
   FILE_GUID                      = E3B7AEF9-4E55-49AF-B035-ED776C928EC6
-  MODULE_TYPE                    = UEFI_DRIVER
+  MODULE_TYPE                    = HOST_APPLICATION
   VERSION_STRING                 = 1.0
-  LIBRARY_CLASS                  = UefiLib|HOST_APPLICATION
+  LIBRARY_CLASS                  = UefiLib
 
 #
 #  VALID_ARCHITECTURES           = IA32 X64 EBC