MdeModulePkg: Add CapsuleOnDiskLoadPei PEIM.

MdeModulePkg: Add CapsuleOnDiskLoadPei PEIM.

https://github.com/tianocore/tianocore.github.io/wiki/UEFI-Capsule-
on-Disk-Introducation

This module provides PPI to load Capsule On Disk temp relocation file
from Root Directory file system, retrieve the capsules from the temp
file and create capsule hobs for these capsules.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Chao B Zhang <chao.b.zhang@intel.com>
Signed-off-by: Wei6 Xu <wei6.xu@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Chao B Zhang <chao.b.zhang@intel.com>