Improve error message when using an under-powered GPU

[emilk]

What

Using scripts/fetch_crashes.py to look at our analytics, I noticed that missing wgpu capabilities would lead to a assert/panic, which is not a nice way to report errors to users.

I added an egui issue to improve this further in the future:

• Allow returning errors from eframe app creator emilk/egui#4474

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
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  • Using examples from latest main build: rerun.io/viewer
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[abey79]

nice