"Set Vertex Colors" should use the active blending mode

"Set Vertex Colors" should use the active blending mode, and instead be called something like Apply Vertex Colors.

"Vertex color from weight" should use the active blending mode aswell.

I often find that I want to utilize the channels of the vertex colors for different things and find myself needing to manually paint brush over the vertices, or set something up in geo nodes, instead of being able to use the above functions.