UIEditor : Added utility `registerWidgetMetadata`
UIEditor : Added utility `registerWidgetMetadata`

And used it to register the simple metadata widgets.

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