web: Implement Device::on_uncaptured_error

[Herschel]

Connections
#2130

Description
This PR is a first pass at wiring up Device::on_uncaptured_error on web, mapping the WebGPU errors into wgpu::Error.

Possible improvements:

• JS does not provide a standardized stack trace on error types, so the Error::source value is bogus.
• Currently the error handler will not be called if an unknown error type is encountered (say, an error is added to the spec).
• Due to using wasm_bindgen::Closure::forget, this will leak the memory associated with the closure. This seemed okay for a one-off diagnostic function, and also can be avoided by enabling weak references, available on all major browsers now. Alternatively, a map would need to be maintained between devices and their error handler.

Testing
Tested it in Ruffle to catch errors thrown by Chrome on certain platforms.

[grovesNL]

Thank you!

Ideally we could have a catch-all and avoid leaking this (using weak references seems reasonable), but we can do that in follow-up PRs