Add custom mouse pointer that is rendered as an element

[James-Livesey]

Using an element-based mouse pointer gives us the advantage of dynamically showing and hiding it depending on if touch events or mouse events are received. It also has the added advantage of being easily customisable, scalable on different displays, and can easily have animations.

We will need to design the custom mouse pointers, preferably as scalable SVGs. We could even dynamically switch the mouse pointer from light to dark mode depending on the current theme (or even the colour the mouse pointer is on) so that it is always easily visible with sufficient contrast.