Add Flag to Make Box Elements Non-Selectable

[dansreis]

Description

We would like to add a feature that allows box elements to be marked as non-selectable. This feature should introduce a flag or property that can be set on box elements, making them non-interactive in terms of selection. This will provide greater control and customization for users who need certain elements to remain static and unselectable.

Motivation

In some use cases, it's necessary to have box elements on the canvas that serve as background or reference elements, which should not be selectable or interactable by the user. Adding this capability will enhance the flexibility of the react-canvas-annotator library and support a wider range of applications.