Playground: Fix connection lengths and let them be based on node input/output types

[abc013]

Related PR: #27759

Description
Previously, it looked like this:

Now, it looks like this:

if demanded, i can remove the other (single-connection) colorings as well. Look into #27759 for further discussion.

[sunag]

Thanks! Why Multiply/Addition output is pink now?

[abc013]

Ah, in- and outputs are pink because they are of the node type. I removed it, we can discuss that particular change in #27759 (and maybe how to retrieve the "real type" of a connection to a socket of type node).

They are now colored in the default color, as it was previously.