[REQUEST] Vertex Color Creation / Modification

Having the ability to add and change vertex color would be super helpful for creating more complex materials. Its also a way to store some simple data within the vert's. I am not sure if this exists or not, but I couldn't find any way do this.

A possible solution would be to have a series of nodes to handle vertex color creation and manipulation. Below are several nodes I would suggest.
- Create Vertex Color Layer (layer name)
- Set Vertex Color for selection (color, alpha, blending mode, layer name)
- Get Vertex Color by index (index, layer name) returns a color and alpha
- Delete Vertex Color Layer (layer name) < for clean up

For the blending mode, I would recommend keeping with the brush blending modes currently in blender. I tried to keep my suggestions in line with how vertex painting in blender currently works, so artists would have an easier time with it.

The issue is about adding vertex color creation and manipulation nodes to a Blender procedural modeling addon. Start by examining the existing node system in the codebase to understand how nodes are defined and integrated. Look for similar material or geometry nodes as a reference. The work involves designing new node types, handling vertex color data layers, and implementing blending modes consistent with Blender's brush system. Testing will require using the addon within Blender to verify the new nodes function correctly in the node editor.

Written by the indexing model from the issue text.