Active Attribute node for node tools

While it is already possible to use any attribute as input for node tools, it's cumbersome because users have to open redo panel and write-in attribute name.

This makes using node tools slow for operators that work on color attributes, or need vertex group as input. To simplify this process, and also make those operators consistent with built-in Blender tools I propose "Active Attribute" node.

This will allow users to simply select attribute, like color attribute or UV map in the properties panel and run the tool. It will automatically detect which one is active and work on that.

This will be especially useful in sculpt mode where you want to create tools for color attributes for more procedural painting.