Fix limits interface on web.

[OptimisticPeach]

Checklist

• Run cargo clippy.
• Run cargo clippy --target wasm32-unknown-unknown if applicable.
• Add change to CHANGELOG.md. See simple instructions inside file.

Connections
Fixes the limits request and reporting api for webgpu backend. Notice that since web_sys doesn't have an impl of requiredLimits for requesting limits, we tack on our own impl as needed (See rustwasm/wasm-bindgen#3587 for more details).

Description
Fills in the api for requesting device limits on the web, fills in the api for reporting device limits, and fixes the api for reporting adapter limits.

Testing
In a minimal wasm app, I run the following:

let adapter = {
    let instance = wgpu::Instance::default();
    instance
        .request_adapter(&wgpu::RequestAdapterOptions::default())
        .await
        .unwrap()
};
let limits = adapter.limits();
let (device, _queue) = adapter.request_device(
    &wgpu::DeviceDescriptor {
        label: None,
        features: Default::default(),
        limits: limits.clone(),
    },
    None,
)
    .await
    .unwrap();
let device_limits = device.limits();
assert_eq!(device_limits, limits);

And see no errors.

[cwfitzgerald]

One last comment, sorry :)