NetworkPkg: Support print help information using -? command.

NetworkPkg: Support print help information using -? command.

v2:
*Modify the logic of show SAD,SPD and PAD help info, include them in -?
instead of follow -p command.

Since Shell supports finding help information from resource section
of application image. We modify the Shell application Under NetworkPkg
to support print help information string using -? command.

Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Wu Jiaxin <jiaxin.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>