Changing the mouse cursor on Canva's React Flow (#420)

## Description

This pull request introduces a new feature that allows users to change
the mouse cursor on Canva's React Flow. By updating the CSS and
JavaScript code, the cursor behavior can be modified to provide a
customized experience for users.

## Motivation

The ability to change the mouse cursor provides a way to enhance user
interaction and personalize the user experience within Canva's React
Flow. This feature can be particularly useful for applications or
websites that require specific cursor styles to match the overall design
or functionality.