Node variadic inputs to represent T as T[]

A node which takes a Vec should be able to expose itself as a variadic input, which looks like this:

| 100% Zoom | 200% Zoom |
|--------|--------|
|  |  |

*(7x14 rectangle with 2px rounding)*

Multiple wires can enter this. The order of the wires entering the variadic input does matter, and it laid out from top to bottom. The node receives these as a Vec of T and otherwise acts normally.

The node macro can define whether a data type, that's a Vec, is shown as variadic or regular. We should also consider whether we support the Table data type, where multiple wires become multiple table rows.