UefiCpuPkg/PiSmmCpuDxeSmm: Add SmmMemoryAttribute protocol

Heap guard makes use of paging mechanism to implement its functionality. But
there's no protocol or library available to change page attribute in SMM mode.
A new protocol gEdkiiSmmMemoryAttributeProtocolGuid is introduced to make it
happen. This protocol provide three interfaces

struct _EDKII_SMM_MEMORY_ATTRIBUTE_PROTOCOL {
  EDKII_SMM_GET_MEMORY_ATTRIBUTES       GetMemoryAttributes;
  EDKII_SMM_SET_MEMORY_ATTRIBUTES       SetMemoryAttributes;
  EDKII_SMM_CLEAR_MEMORY_ATTRIBUTES     ClearMemoryAttributes;
};

Since heap guard feature need to update page attributes. The page table
should not set to be read-only if heap guard feature is enabled for SMM
mode. Otherwise this feature cannot work.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>