MdeModulePkg: SmmSmiHandlerProfileLib: Support StandaloneMm Instance

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3185

This change added support of SMI handler profile library router under
StandaloneMm. This change replaces gSmst with gMmst. It also abstracts
standalone and traditional MM driver entrypoints into separate files to
allow maximal common implementations.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>

Signed-off-by: Kun Qin <kun.q@outlook.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>

MdeModulePkg/Library/SmmSmiHandlerProfileLib/StandaloneMmSmiHandlerProfileLib.c

@@ -0,0 +1,31 @@
+/** @file
+  Standalone MM driver instance of SmiHandlerProfile Library.
+
+  Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) Microsoft Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <PiMm.h>
+
+#include "MmSmiHandlerProfileLib.h"
+
+/**
+  The constructor function for standalone MM SMI handler profile.
+
+  @param  ImageHandle   The firmware allocated handle for the EFI image.
+  @param  SystemTable   A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
+**/
+EFI_STATUS
+EFIAPI
+StandaloneMmSmiHandlerProfileLibConstructor (
+  IN EFI_HANDLE           ImageHandle,
+  IN EFI_MM_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return MmSmiHandlerProfileLibInitialization ();
+}
+