This patch allows passing a field to the modifier as output. In the modifier, the user can choose an attribute name. The attribute will be filled with values computed by the field. This only works for realized mesh/curve/point data. As mentioned in T91376, the output domain is selected in the node group itself. We might want to add this functionality to the modifier later as well, but not now. Differential Revision: https://developer.blender.org/D12644