ShellPkg: Add AcpiViewCommandLib

ShellPkg: Add AcpiViewCommandLib

The UefiShellAcpiViewCommandLib is converted from NULL library to a
named library so that it may be used in modules other than shell.
The library interface exposes the main method for to AcpiView
functionality as well as a helper method to dump a buffer to a file.

The Shell module is still built by pulling UefiShellAcpiViewCommandLib
as a NULL library to preserve the modularity of shell builds.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Signed-off-by: Tomas Pilar <tomas.pilar@arm.com>