PrmPkg: Add package and include headers

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3812

Adds a new package to maintain Platform Runtime Mechanism (PRM)
support.

This package is intended to include generic code that provides a
common infrastructure to support PRM in firmware and a collection
of sample PRM modules that demonstrate how to use the interfaces
and other package resources to author a PRM module.

The following initial headers are included in this commit:

* Prm.h - Includes common content for PRM with no dependencies on
  other PRM header files.

* PrmContextBuffer.h - Includes definitions for PRM context buffers.

  Context buffers are standardized structures that point to various
  resources available to a PRM handler during its execution.

* PrmDataBuffer.h - Includes definitions for PRM data buffers.

  Within the context of PRM, these data buffers are composed of a
  generic header followed by a variable length blob of arbitrary
  data.

* PrmExportDescriptor.h - Includes definitions for  creating PRM
  export descriptors.

  A PRM export descriptor is a structure referenced in the export
  table of PRM module that contains PRM-specific metadata about the
  module.

* PrmMmio.h - Includes definitions for describing MMIO ranges uses
  by PRM modules.

* PrmModule.h - Includes definitions commonly used by PRM module
  authors.

  This file is provided to serve as a convenient include for PRM
  module authors.

* PrmOsServices.h - Includes content specific to PRM OS services.

  OS Services will not planned to be present in the final version
  of PRM. The OS Services have been reduced to a simple debug print
  function. So this is currently planned to be a temporary file to
  support debugging during PRM development.

Note: Modules built for the UEFI environment can be built by Visual
      Studio and non-Visual Studio toolchains. However, PRM modules
      are currently only supported on Visual Studio toolchain due to
      usage of export tables.

Cc: Andrew Fish <afish@apple.com>
Cc: Kang Gao <kang.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Liu Yun <yun.y.liu@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>

PrmPkg/Include/PrmMmio.h

@@ -0,0 +1,45 @@
+/** @file
+
+  Definitions for the Platform Runtime Mechanism (PRM) MMIO elements.
+
+  Copyright (c) Microsoft Corporation
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef PRM_MMIO_H_
+#define PRM_MMIO_H_
+
+#include <Uefi.h>
+
+#pragma pack(push, 1)
+
+///
+/// Describes a memory range that needs to be made accessible at OS runtime.
+///
+/// The memory range with the given base address and length will be marked as EFI_MEMORY_RUNTIME.
+///
+typedef struct {
+  EFI_PHYSICAL_ADDRESS                    PhysicalBaseAddress;
+  EFI_PHYSICAL_ADDRESS                    VirtualBaseAddress;
+  UINT32                                  Length;
+} PRM_RUNTIME_MMIO_RANGE;
+
+///
+/// Describes a buffer with an array of PRM module
+/// config runtime memory ranges.
+///
+typedef struct {
+  ///
+  /// The number of runtime memory range elements in this buffer.
+  ///
+  UINT64                                  Count;
+  ///
+  /// The beginning of the runtime memory range data.
+  ///
+  PRM_RUNTIME_MMIO_RANGE                  Range[1];
+} PRM_RUNTIME_MMIO_RANGES;
+
+#pragma pack(pop)
+
+#endif