ClevoOpenBoardPkg/N1xxWU: Add headers

Based on KabylakeOpenBoardPkg from the following branch:
https://github.com/tianocore/edk2-platforms/tree/devel-MinPlatform



Header files for the N1XXWU Clevo board instance.

* PeiPchPolicyUpdate.h - Shared interfaces and includes used for
  Platform Controller Hub (PCH) initialization in
  PeiSiliconPolicyUpdateLibFsp.
* PeiSaPolicyUpdate.h - Shared interfaces and includes used for
  System Agent (SA) initialization in PeiSiliconPolicyUpdateLibFsp.
* N1xxWUId.h - The board IDs for N1xxWU boards. Exposed for use
  in libraries/modules in the N1xxWU directory.
* PeiN1xxWUInitLib.h - Shared interfaces and includes for the
  N1xxWU PEI board initialization library.
* DxeGopPolicyInit.h - Shared interfaces and includes used for GOP
  policy initialization in DxeSiliconPolicyUpdateLib.
* DxeSaPolicyInit.h - Shared interfaces and includes used for
  System Agent (SA) initialization in DxeSiliconPolicyUpdateLib.

Cc: Hao Wu <hao.a.wu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>