ShellPkg: Remove ShellPkg wrapper header files

ShellPkg: Remove ShellPkg wrapper header files

These wrapper header files are not referenced by all
open source, so they are removed.
https://bugzilla.tianocore.org/show_bug.cgi?id=158

Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>