MdeModulePkg and Nt32Pkg Pcd: Add the new EFI_GET_PCD_INFO_PROTOCOL and EFI_GET_PCD_INFO_PPI support for PI 1.2.1 compliance.

It has no obviously benefit to reduce size by PcdPcdInfoGeneration, so remove this PCD.
And PCD_INFO_GENERATION flag can be used to enable/disable PCD info feature, a sample is added in Nt32Pkg to show how to use this flag.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg@14869 6f19259b-4bc3-4df7-8a09-765794883524