The absence of the channel was causing pytorch not to be found on
a windows installation (windows 10 22H2, miniconda3, conda 24.4.0)

task_slice.py:
- Checkbox for enabling the 3D mask edit
- Button for performing the edit
- Combobox for choosing the edit mode

constants.py:
- Style ID for mask edit
- Operation constants and mode strings (not localized yet)

UI modifications to allow drawing a polygon in the volume renderer

- Canvas Handler for simple polygon selection and rendering;
- Interaction style to create this polygon and communicate to mask edit.

Functionality for using the polygon drawn in the volume viewer to cut
the mask has been implemented.

The user can now select multiple polygons in the volume renderer to
perform the edit.

Added controls in task_slice for toggling the "3D mask cut with depth"
functionality.
Added the button for cleaning up the polygons in the volume viewer.

Implemented with a spin control from 0 to 1.

Function parameter improvements in mask_3d_edit.py

Fixed the problem by inverting the Y axis