fix: replace rate-limiter

[achingbrain]

rate-limiter-flexible is a CJS module with a single export of all it's various implementations.

This defeats tree shaking resulting in the addition of 42KB to the bundle size.

animir/node-rate-limiter-flexible#249

This PR brings the source & tests for the in-memory rate limiter into @libp2p/utils which reduces the bundle size increase to a few KBs.

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works

[wemeetagain]

LGTM

[mroderick]

This issue is really a shortcoming of your bundler/treeshaker and not of rate-limiter-simple.

However, there's hope.

Since you're using ESM, you can deep import files from packages, instead of using the root file.

import RateLimiterMemory from "rate-limiter-flexible/lib/RateLimiterMemory.js";

console.log(typeof RateLimiterMemory);
// => function

That means that you don't need to copy RateLimiterMemory to your own codebase and keep it up to date as the source version changes.