Very large bundle size
When using the in-memory rate limiter in browsers it results in a bundle addition of 42KB:

<img width="251" alt="image" src="https://github.com/animir/node-rate-limiter-flexible/assets/665810/2c88b63f-0574-4854-82fc-c0128383893b">

If I pull just the depended on files out of this module it's more like 4KB:

<img width="533" alt="image" src="https://github.com/animir/node-rate-limiter-flexible/assets/665810/7167fed1-9e64-4f94-83b6-bfb1ddb9d0ab">

I think this is because this module is CJS and exports all the various implementations [in one blob](https://github.com/animir/node-rate-limiter-flexible/blob/master/index.js#L15-L31) which makes tree shaking impossible.

Could this module be updated to be ESM with only named exports?

