refactor: Organize Canvas Utilities and BPP Format Management

- Moved canvas utility functions into a dedicated `canvas_utils` module for better structure and maintainability.
- Introduced a new `BppFormatUI` class for managing BPP format selection and conversion, enhancing the user interface for format management.
- Updated CMake configuration to include new source and header files for the canvas utilities and BPP format UI.
- Adjusted file paths in the project structure to reflect the new organization, ensuring proper integration across components.

src/app/gui/gui_library.cmake

@@ -6,14 +6,14 @@ set(
   app/gui/widgets/dungeon_object_emulator_preview.cc
   app/gui/widgets/collaboration_panel.cc
   app/gui/canvas.cc
-  app/gui/canvas_utils.cc
+  app/gui/canvas/canvas_utils.cc
   app/gui/widgets/palette_widget.cc
   app/gui/widgets/palette_editor_widget.cc
   app/gui/input.cc
   app/gui/style.cc
   app/gui/color.cc
   app/gui/theme_manager.cc
-  app/gui/bpp_format_ui.cc
+  app/gui/canvas/bpp_format_ui.cc
   app/gui/widgets/widget_id_registry.cc
   app/gui/widgets/widget_auto_register.cc
   app/gui/widgets/widget_state_capture.cc