Add image selection refinement functionality with BEN2 integration

- Implemented viewport.py for handling 3D view projections, gestures, and overlay drawing.
- Created refine_image_selection.py to manage the refinement of gesture masks and output image bounds.
- Added selection module with refine_selection.py to process and crop images based on alpha channel visibility.
- Introduced __init__.py for selection module to expose refine_selection function.

src/anyimage/menu.py

@@ -1,6 +1,6 @@
 import bpy
 
-from .common.image_data import is_image_empty
+from .common.image import is_image_empty
 from .operators.upscale import upscale_output_size