UefiCpuPkg: Add SecCore module and supporting library class and PCD

UefiCpuPkg: Add SecCore module and supporting library class and PCD

Add declaration of PlatformSecLib library class to DEC file
Add declaration of PcdPeiTemporaryRamStackSize PCD to DEC/UNI file
Add build of PlatformSecLibNull to DSC file
Add build of SecCore to DSC file

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18637 6f19259b-4bc3-4df7-8a09-765794883524