Part 1 of #21713
Changes:
- Remove `.present()` and add a `presentGPUCanvasContext` (not exposed
yet to users)
- Move lazy load logic to `00_init.js`. This can be used to use webgpu
on-demand from future code (OffScreenCanvas)
This PR _**temporarily**_ removes WebGPU (which has behind the
`--unstable` flag in Deno), due to performance complications due to its
presence.
It will be brought back in the future; as a point of reference, Chrome
will ship WebGPU to stable on 26/04/2023.
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Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
