Feedback Expose AdvancedDropdownGUI to allow users to override DrawItem

I'm a fan of the AdvancedDropdown class. I like how it is in-line with the rest of the Unity user interface when I use it in my own tooling. However, I'd like to customize the dropdown further.

For example, I would want to add multiple icons to each row or simply customize the drawing of a single row item. Currently, the required API to do so is internal, e.g. AdvancedDropdownGUI.DrawItem. By making it public and with a few slight modifications it would be possible to implement such custom drawing.

I realize that Unity is probably focusing on UI Elements at the moment, but my request would also hold true if the AdvancedDropdown was converted to the new API. I always like to use unified controls such as this dropdown or the reorderable list and then customize as much as possible.