UefiPayloadPkg: Remove PEI phase from Payload

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3100

It is not necessary to have a PEI phase in the UEFI payload since no
specific PEI task is required. This patch adds a UefiPayloadEntry
driver to get UEFI Payload required information from the bootloaders,
convert them into a HOB list, load DXE core and transfer control to it.

Here is the change details:
1) Removed PEI phase, including Peicore, BlSupportPei, SecCore, etc.
2) Added UefiPayloadEntry driver. this is the only driver before DXE core.
3) Added Pure X64 support, dropped Pure IA32 (Could add later if required)
   64bit payload with 32bit entry point is still supported.
4) Use one DSC file UefiPayloadPkg.dsc to support X64 and IA32X64 build.
   Removed UefiPayloadIa32.dsc and UefiPayloadIa32X64.dsc

Tested with SBL and coreboot on QEMU.

Signed-off-by: Guo Dong <guo.dong@intel.com>
Reviewed-by: Maurice Ma <maurice.ma@intel.com>
Reviewed-by: Benjamin You <benjamin.you@intel.com>

UefiPayloadPkg/Library/HobLib/HobLib.inf

@@ -0,0 +1,39 @@
+#/** @file
+#
+#  Copyright (c) 2018 - 2020, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#
+#**/
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = HobLib
+  FILE_GUID                      = AD6B4D55-8DBE-48C8-88E3-CFDBB6E9D193
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = HobLib
+
+#
+#  VALID_ARCHITECTURES           = IA32 X64 EBC
+#
+
+[Sources.common]
+  Hob.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  UefiPayloadPkg/UefiPayloadPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugLib
+
+[Guids]
+  gEfiHobMemoryAllocModuleGuid
+  gEfiHobMemoryAllocStackGuid
+