MdeModulePkg: Rename IS_ALIGNED macros to avoid name collisions

This patch is a preparation for the patches that follow. The
subsequent patches will introduce and integrate new alignment-related
macros, which collide with existing definitions in MdeModulePkg.
Temporarily rename them to avoid build failure, till they can be
substituted with the new, shared definitions.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>