Add flag to ignore `index.html` resolution in gateway

At the moment, if I want to do a directory listing using an HTTP request to a gateway, I cannot do anything if there is an `index.html` file inside a given path.

It would be nice to be able to specify a flag in the querystring (eg, `?noResolve`) to skip the resolution of `index.html` and to do a regular directory read.

This is something I've played with a bit in [js-ipfs-fetch](https://github.com/RangerMauve/js-ipfs-fetch#await-fetchipfscidexample-headers-x-resolve-none) using a custom header, but that doesn't play well with CORS and I've since learned that querystrings are much more reliable/ usable (in [hypercore-fetch](https://github.com/RangerMauve/hypercore-fetch#fetchhypernameexampletxtnoresolve-method-get)).

Is this something that could be considered for addition?