Support multiple windows

[kvark]

In Zed, we are initializing a graphics context for every window. However, if there is more than one window, we are wasting time re-initializing the connection to the graphics driver, recompiling all the pipelines, etc. If we support multiple windows natively, we could save that time.

[MatinAniss]

What is required for this to be implemented and what would the implementation look like?

[kvark]

We'd need to introduce Window as a new type of things. It would be created from the Context. Overall, I haven't thought through the details of how this will work. I typically start prototyping it to see the issues that would arise and then design as I go.