feat(dashboard): distinguish parent and child relations on a graph

[VladyslavG]

I had a task to refactor some fixtures in the Codux. I decided to use our feature graph for that and it was really useful. However when viewing feature graph I noticed that all links - parent and child are highlighted in the same color. I could not understand looking at a graph where was my feature requested as a child. Take a look at this:

I hovered over file-assets and it is impossible to tell which related feature uses file-assets vs which is used by file-assets.

So I propose to use different colors for parent links vs child links. I used this approach personally in my abovementioned task and it helped me a lot! So I decided to create this PR, maybe it will help other people when playing with features

After applying my changes:

You can clearly see different colored lines and distinguish parent vs child relations. If you don't like the suggested color, please feel free to fix it.