MdePkg/Include/Base.h: introduce the ARRAY_SIZE() function-like macro

MdePkg/Include/Base.h: introduce the ARRAY_SIZE() function-like macro

Several modules use ARRAY_SIZE() already; centralize the definition. (The
module-specific macro definitions are guarded by #ifndef directives at
this point.)

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Cecil Sheng <cecil.sheng@hpe.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Daryl McDaniel <edk2-lists@mc2research.org>
Cc: David Wei <david.wei@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Gary Lin <glin@suse.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Tim He <tim.he@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>