UGizmoBaseVec2ParameterSource

[UGizmoBaseVec2ParameterSource](API\Runtime\InteractiveToolsFramework\BaseGizmos\UGizmoBaseVec2ParameterSource) is a base implementation of [IGizmoVec2ParameterSource](API\Runtime\InteractiveToolsFramework\BaseGizmos\IGizmoVec2ParameterSource), which is not functional but adds an OnParameterChanged delegate for further subclasses.