MdePkg: Add MdeLibs.dsc.inc file to MdePkg

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3246

MdeLibs.dsc.inc is added for some default libraries provided by MdePkg.
Platform can include MdeLibs.dsc.inc file to avoid some potential
incompatible changes to platform dsc file in future.

Only add RegisterFilterLib into it as the first version of MdeLibs.dsc.inc.
Can update and maintain MdeLibs.dsc.inc gradually later.

"MdeLibs.dsc.inc" for the [LibraryClasses*] section(s)

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

MdePkg/MdeLibs.dsc.inc

@@ -0,0 +1,15 @@
+## @file
+# Mde DSC include file for [LibraryClasses*] section of all Architectures.
+#
+# This file can be included to the [LibraryClasses*] section(s) of a platform DSC file
+# by using "!include MdePkg/MdeLibs.dsc.inc" to specify the library instances
+# of some EDKII basic/common library classes.
+#
+# Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+#
+#    SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[LibraryClasses]
+  RegisterFilterLib|MdePkg/Library/RegisterFilterLibNull/RegisterFilterLibNull.inf