ShellPkg/ShellLib: Constructor doesn't depend on ShellParameters

When ShellLib is linked to a driver producing DynamicCommand
protocol, ShellParameters protocol is set by
DynamicCommand.Handler().
The driver image handle doesn't have ShellParameters protocol
installed.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>