UnitTestFrameworkPkg: Add subhook submodule required for gmock

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

Add subhook submodule that is required to hook internal functions
when using gmock.

    https://github.com/Zeex/subhook

Add SubhookLib library class and SubhookLib library instance.
Include the SUBHOOK_STATIC define in the SubhookLib INF file so
it builds as a static library. Also include the SUBHOOK_STATIC
define in SubhookLib.h so all modules using SubhookLib properly
link SubhookLib as a static library.

Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <mikuback@linux.microsoft.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Signed-off-by: Chris Johnson <chris.n.johnson@intel.com>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Oliver Smith-Denny <osde@linux.microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

UnitTestFrameworkPkg/Library/SubhookLib/SubhookLib.inf

@@ -0,0 +1,31 @@
+## @file
+#  This module provides Subhook Library implementation.
+#
+#  Copyright (c) 2022, Intel Corporation. All rights reserved.<BR>
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION     = 0x00010018
+  BASE_NAME       = SubhookLib
+  MODULE_UNI_FILE = SubhookLib.uni
+  FILE_GUID       = 70E03378-E140-46A8-8E65-7719DA14A240
+  MODULE_TYPE     = HOST_APPLICATION
+  VERSION_STRING  = 0.1
+  LIBRARY_CLASS   = SubhookLib
+
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  subhook/subhook.c
+
+[Packages]
+  UnitTestFrameworkPkg/UnitTestFrameworkPkg.dec
+
+[BuildOptions]
+  MSFT:*_*_*_CC_FLAGS   == /c /EHsc /Zi /DSUBHOOK_STATIC /Od
+  GCC:*_*_IA32_CC_FLAGS == -g -c -O0 -m32
+  GCC:*_*_X64_CC_FLAGS  == -g -c -O0 -m64