SecurityPkg: PlatformPKProtectionLib: Added PK protection interface

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3911

This patch provides an abstracted interface for platform to implement PK
variable related protection interface, which is designed to be used when
PK variable is about to be changed by UEFI firmware.

This change also provided a variable policy based library implementation
to accomodate platforms that supports variable policy for variable
protections.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Min Xu <min.m.xu@intel.com>

Signed-off-by: Kun Qin <kun.qin@microsoft.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Michael Kubacki <michael.kubacki@microsoft.com>

SecurityPkg/Include/Library/PlatformPKProtectionLib.h

@@ -0,0 +1,31 @@
+/** @file
+  Provides an abstracted interface for configuring PK related variable protection.
+
+  Copyright (c) Microsoft Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef PLATFORM_PK_PROTECTION_LIB_H_
+#define PLATFORM_PK_PROTECTION_LIB_H_
+
+/**
+  Disable any applicable protection against variable 'PK'. The implementation
+  of this interface is platform specific, depending on the protection techniques
+  used per platform.
+
+  Note: It is the platform's responsibility to conduct cautious operation after
+        disabling this protection.
+
+  @retval     EFI_SUCCESS             State has been successfully updated.
+  @retval     Others                  Error returned from implementation specific
+                                      underying APIs.
+
+**/
+EFI_STATUS
+EFIAPI
+DisablePKProtection (
+  VOID
+  );
+
+#endif