Reduce input latency by switching to double-buffered rendering

[emilk]

This makes a huge difference in perceived latency on my 60 Hz monitor on macOS on a native build, e.g. when hovering buttons, or just the distance between the cursor and the hover-window when hovering an image.

It does produce some tearing, noticable e.g. when quickly panning a 2D image. To me the trade-off is absolutely worth it: tearing is a mild visual glitch that shows up occationally, input latency is a constant irritation, making an application feel sluggish.

It makes no difference on web though, so this does NOT solve #2672

I also switched the defaults in eguo-wgpu: emilk/egui#3714

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  • Using newly built examples: app.rerun.io
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[Wumpf]

Related to:

• Extended Presentation API Investigation gfx-rs/wgpu#2869

[Wumpf]

• Blocked by Expose maximum_frame_latency gfx-rs/wgpu#4899

[teh-cmc]

Drafting to reduce visual clutter in the pending-review queue

[emilk]

Closed in favor of emilk/egui#3874