Explore GPU rendering in the editor

[Tyriar]

I did an exploration recently into using webgl in the editor by forking/integrating xterm.js' renderer into monaco. The results look very promising, here is a summary:

• There are big wins to FPS/scrolling performance and overall smoothness of the application, especially for average/old hardware.
• We could introduce an experimental renderer and progressively "upgrade" parts of Monaco as needed
• Regardless of whether we pursue GPU acceleration, we should fine tune input latency performance Optimize editor for input latency #161622

Exploration branch: https://github.com/microsoft/vscode/tree/tyriar/webgl_monaco

[Tyriar]

Closing as the exploration was done, we may or may not do this in the future. The main concern is it's a lot of effort to create and maintain given my experience doing the terminal renderer. Especially since monaco relies on a lot of DOM functionality and accessibility is a big headache when using canvas.

[Tyriar]

New issue for this feature: #221145