DHT validator / selector

[vasco-santos]

I am writing the interop tests for the DHT between js and go and I am having an issue with the keys.

Using js-ipfs and go-ipfs daemon, we are able to put / get any type of keys, while it doesn't seem to be the case with go-libp2p. In this context, I think that we should be able to set custom validators/selectors as we are able to do when using the DHT module. Moreover, regarding testing the interop between get and put will be more complex since we would have to use a valid namespace such as ipns and put a valid record.

Example in go tests for custom validators/selectors: libp2p/go-libp2p-kad-dht/dht_test.go#L51