Add gpu-curtains based transitions

[gunta]

The WebGPU based transitions are just too cool to not have them embedded in slidev. No other web slideshow library has WebGPU effects so it adds to the Wow Effect™️.

[kermanx]

Sorry, I can't open the example 🥺

[gunta]

Can't reproduce here. Looks like a CORS problem.

You might want to try with the latest or dev Chrome, with WebGPU enabled, disabling extensions or firewalls that might be causing the error.