Integrate Desktop Vision

Notes:

• This code integrates desktop vision into vartiste so that users can control their computer while painting in VR
• Desktop Vision has been added to its own file src/desktop-vision.js that is required in src/index.js
• Desktop Vision registers its own Util.registerComponentSystem
• The Desktop Vision script is loaded asynchronously upon the initialization
• The script loads immediately in order to handle a redirect oauth flow
• Desktop Vision computers are added to an a-entity which is subsequently added to the scene

Flow:

• Buttons to use Desktop vision can be accessed through the experimental functionality toolbar
• Users are taken through an oauth flow that prompts them to select a computer
• When the user returns from the flow, their computer will be visible & controllable in the scene
• Desktop Vision automatically adds resize & move icons for the user to move their computer around & resize