Extend Connection Line props

Include Node and Handle in props passed to custom connection lines for advanced usage.

src/components/ConnectionLine/index.tsx

@@ -79,6 +79,8 @@ export default ({
           targetPosition={targetPosition}
           connectionLineType={connectionLineType}
           connectionLineStyle={connectionLineStyle}
+          sourceNode={sourceNode}
+          sourceHandle={sourceHandle}
         />
       </g>
     );

src/types/index.ts

@@ -303,6 +303,8 @@ export type ConnectionLineComponentProps = {
   targetPosition?: Position;
   connectionLineStyle?: CSSProperties;
   connectionLineType: ConnectionLineType;
+  sourceNode?: Node | null;
+  sourceHandle?: HandleElement;
 };
 
 export type ConnectionLineComponent = React.ComponentType<ConnectionLineComponentProps>;