MdeModulePkg: introduce UEFI freed-memory guard bit in HeapGuard PCD

MdeModulePkg: introduce UEFI freed-memory guard bit in HeapGuard PCD

UAF (Use-After-Free) memory issue is kind of illegal access to memory
which has been freed. It can be detected by a new freed-memory guard
enforced onto freed memory.

BIT4 of following PCD is used to enable the freed-memory guard feature.

  gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask

Please note this feature is for debug purpose and should not be enabled
in product BIOS, and cannot be enabled with pool/page heap guard at the
same time. It's disabled by default.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>