This adds attribute search to the geometry nodes modifier for the input and output attributes. The "New" search item is only shown for the output attributes. Some of the attribute search code is extracted to a new file in the interface code, to avoid some code duplication. The UI code required two fixes so that the search would work for dynamic length strings (IDProperties do not have a fixed size). Since this does changes to the UI layout of the modifier, I also addressed T91485 here. Differential Revisiion: https://developer.blender.org/D12788