[Enhancement] A collection of pre-included plugins

[conorvenus]

What do you think about the potential of having some premade plugins included in the library? For example, if people are serving their website via CF or another reverse proxy, the clients' IP addresses are obscured and so you have to use the CF-Connecting-IP header, otherwise then you just end up ratelimiting CF's IP (e.g., every single user who wants to access that endpoint is now ratelimited).

export class CloudflareRateLimiter implements RateLimiterPlugin {
    readonly rate: Rate;

    constructor(rate: { limit: number, duration: RateUnit }) {
        this.rate = [rate.limit, rate.duration];
    }

    async hash(event: RequestEvent) {
        return event.request.headers.get('cf-connecting-ip') || event.getClientAddress();
    }
}

[ciscoheat]

Good idea, I'll add this one to a limiters directory in the next release, then you can make a PR there if you want to add more.

[ciscoheat]

Added now in 0.6.1. Can you make a PR for the Readme to include them?

CloudflareIPRateLimiter and CloudflareIPUARateLimiter that can be imported from sveltekit-rate-limiter/limiters.