Based on the design in #120230.
* Replaces the `Shade Smooth by Angle` operator with `Shade Auto Smooth`
in the object context menu menu.
* The new operator automatically adds and removes the modifier instead
of being a destructive operation.
* The `Shade Smooth` and `Shade Flat` operators now remove the
`Smooth by Angle` modifier automatically.
* Add a pin option to modifiers, which limits dragging and keeps the
modifier after newly added modifiers in the list.
Co-authored-by: Hans Goudey <hans@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/121494
2f289857af