Add related lines when dragging a node

[ziqyang-ebay]

When we are dragging a node, instead of having the original node and its related lines showing as well as the new position, we hope that there can be corresponding lines added to the moving node.

In the long term, we want a node and corresponding lines to move in real-time when we drag a node.
As for now, we decide to use opacity to hide the original node and its lines, but then there will only be the new node but no lines on the canvas, which is weird.