Hidden dom

[btzr-io]

Create an accessible hidden layer DOM.
This is something similar to what other engines provide, like pixi.js:
https://pixijs.download/release/docs/accessibility.html

Upcoming changes for pixi js implementation looks interesting:
pixijs/pixijs#11107

Generating the dom is pretty simple, all is left is to figure out how to position and scale the elements to match the Godot canvas.