MdePkg: Add TdxLib to wrap Tdx operations

RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

TdxLib is created with functions to perform the related Tdx operation.
This includes functions for:
 - TdAcceptPages   : Accept pending private pages and initialize the pages
                     to all-0 using the TD ephemeral private key.
 - TdExtendRtmr    : Extend measurement to one of the RTMR registers.
 - TdSharedPageMask: Get the Td guest shared page mask which indicates it
                     is a Shared or Private page.
 - TdMaxVCpuNum    : Get the maximum number of virtual CPUs.
 - TdVCpuNum       : Get the number of virtual CPUs.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>

MdePkg/Library/TdxLib/TdxLib.inf

@@ -0,0 +1,37 @@
+## @file
+# Tdx library
+#
+#  Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = TdxLib
+  FILE_GUID                      = 032A8E0D-0C27-40C0-9CAA-23B731C1B223
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = TdxLib
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources.IA32]
+  TdxLibNull.c
+
+[Sources.X64]
+  AcceptPages.c
+  Rtmr.c
+  TdInfo.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugLib