IntelFsp2WrapperPkg: Support UPD allocation outside FspWrapper

IntelFsp2WrapperPkg: Support UPD allocation outside FspWrapper

UPD allocation and patching can be done outside FspWrapper
as implementation choice so adding a PCD to select between
original FspWrapper allocation model or outside model

Cc: Jiewen Yao <Jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>