LabelPlugValueWidget : Support dynamic "label" metadata that uses `getName()`
LabelPlugValueWidget : Support dynamic "label" metadata that uses `getName()`

Fixes
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- LabelPlugValueWidget : Fixed bug that prevented updates if the `label` metadata depended on the plug name.

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