This patch adds support for drag and dropping colors (from color buttons) into
the Compositing, Shading and Geometry node trees.
Additional support was added for dragging and dropping colors with an Alpha
component (which was previously ignored), both in the context of the Node Editor
and for Color Buttons in general. This handles cases like drag and dropping a
color from an RGB to an RGBA button, which recreates the color with a default
Alpha value of 1.0.
Pull Request: https://projects.blender.org/blender/blender/pulls/129026