MdeModulePkg: Add Capsule On Disk related definition.

MdeModulePkg: Add Capsule On Disk related definition.

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

This patch will add Capsule On Disk related definition, including
GUID, PPI and PCDs:
The Capsule On Disk Name GUID indicates the capsule is to store
Capsule On Disk file names.
The Pei Capsule On Disk PPI provides service to retrieve capsules
from Capsule On Disk temp relocation file on mass storage devices
and create capsule hob for these capsules.
Pei Boot In CapsuleOnDisk Mode Ppi indicates current boot mode is
capsule on disk mode.
PcdCapsuleOnDiskSupport is used to enable/disable Capsule On Disk.
PcdCapsuleInRamSupport is used to enable/disable Capsule In Ram.
PcdCoDRelocationFileName specifies the Capsule On Disk temp
relocation file name.
PcdCodRelocationDevPath specifies platform specific device to store
Capsule On Disk temp relocation file.

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>