Adds a new node to set the Grease Pencil depth ordering. Here are the options: * 2D Layers: Uses the Layer order + Stroke order to calculate the depth ordering. * 3D Location: Uses the 3D position of the points as the depth. This reflects the same setting that is available in the Grease Pencil object-data properties. The node is added to the `Grease Pencil` > `Write` menu. Resolves #129458. Pull Request: https://projects.blender.org/blender/blender/pulls/135914