ShellPkg/AcpiView: Refactor configuration

ShellPkg/AcpiView: Refactor configuration

A new file and header (AcpiViewConfig.[ch]) is created
that houses the user configuration. This declutters the
core code and improves modularity of the design.

The module level symbols for verbosity, table selection, and
highlighting are refactored into the new file.

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>