Make a browser compatible rate limiter

[playfulkittykat]

Noticed I was hitting the rate limit in my web app, so here's an implementation of the rate limiter that works in the browser.

It's in its own crate to keep the dependency tree manageable. If the rate-limit feature is not enabled, no additional dependencies are compiled. On the other hand, if it is enabled, only the platform specific dependencies are compiled. I'm not sure there's a way to mix target.'cfg(...)'.dependencies and features otherwise.

Further investigation is needed to know if the OPTIONS + POST request pattern required by CORS counts as two API requests.

[nasso]

i think it should be possible to enable dependencies when a feature is enabled

[playfulkittykat]

You can, yes. Using the feature-name = ["crate"] syntax. I'm just not sure how to mix that with target.cfg(...).dependencies.

I don't want to depend on tokio when compiling for WASM nor on gloo-timers when compiling for x86.

[playfulkittykat]

Oh, actually, I just figured it out.

[nasso]

the two files have a lot of code in common, they could maybe just be the same file with 2-3 #[cfg(...)] here and there

but if that works for you it looks good to me! thank you for your contributions!