Setting `sourceLayerIdentifier` on `LineStyleLayer` has no effect

`sourceLayerIdentifier` is not copied [here](https://github.com/maplibre/swiftui-dsl/blob/59fc604dfd9ba68de22b641f91ffc5cd579bc20a/Sources/MapLibreSwiftDSL/Style%20Layers/Line.swift#L72-L83).