Clear layour for better readibility of labels in graphs

[colobrodo]

Is your feature request related to a problem? Please describe.
Hi, I'm trying to use rerun to make a visualisation of parts of webgraph, which are huge graphs with many nodes. Some nodes are very dense and the default visualisation is difficult to use:

• the edges' arrows cover other nodes
• Labels cover each other and are hard to read if not selected.

Describe the solution you'd like
I think the visualisation can be more useful if the arrows are slightly transparent by default to be able to read what is underneath, or transparent unless an adjacent node is selected.
For the labels, I think it would be more readable if they just came up once selected or on mouse-over.

Additional context
I've provided an example that describes what I'm referring to in the issue (sorry, but I have to compress it because github won't allow me to upload rrd files).

Thanks!
cnr-2000-node-31415-depth-2.zip