Added Leaflet.DivIcon for icon type (#14736)

* Added Leaflet.DivIcon for icon type

* Changed icon to BaseIcon type, as per @danzel suggestion

react-leaflet/index.d.ts

@@ -111,7 +111,7 @@ interface LayerProps extends LeafletInteractionEvents {
 interface MarkerProps extends LayerProps, LeafletDraggingEvents {
     position: Leaflet.LatLngExpression;
     draggable?: boolean;
-    icon?: Leaflet.Icon;
+    icon?: Leaflet.BaseIcon;
     zIndexOffset?: number;
     opacity?: number;
 }

react-leaflet/react-leaflet-tests.tsx

@@ -179,6 +179,18 @@ export class CustomComponent extends Component<any, any> {
     }
 }
 
+export class MarkerWithDivIconExample extends Component<any, any> {
+    render() {
+        return (
+            <Map>
+                <Marker position={[0, 0]} icon={
+                        new Leaflet.DivIcon({})
+                    }/>
+            </Map>
+        )
+    }
+}
+
 // draggable-marker.js
 export class DraggableExample extends Component<any, any> {
     state = {