Fix: Curves: Missing brush assets selector in curves sculpt mode

All sculpt and paint modes should have the brush selector asset shelf
popup in the tool settings header. For curves sculpt mode this was
missing. There's no good reason for this, probably just an oversight.

scripts/startup/bl_ui/space_view3d.py

@@ -539,8 +539,10 @@ class _draw_tool_settings_context_mode:
 
         tool_settings = context.tool_settings
         paint = tool_settings.curves_sculpt
-
         brush = paint.brush
+
+        BrushAssetShelf.draw_popup_selector(layout, context, brush)
+
         if brush is None:
             return False