GafferArnoldUI : Removed explicit use of PathPlugValueWidget.
GafferArnoldUI : Removed explicit use of PathPlugValueWidget.

This is now used via metadata registrations. Also replaced a couple of other explicit registrations which can now be achieved via metadata.

lucienfostier/gaffer,boberfly/gaffer,ImageEngine/gaffer,chippey/gaffer,boberfly/gaffer,chippey/gaffer,johnhaddon/gaffer,hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,chippey/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,hradec/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,hradec/gaffer,boberfly/gaffer,boberfly/gaffer,hradec/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,ImageEngine/gaffer,ivanimanishi/gaffer,chippey/gaffer,lucienfostier/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer