This allows Kubo to respond to the GetClosestPeers() http routing v1 endpoint
as spec'ed here: https://github.com/ipfs/specs/pull/476
It is based on work from https://github.com/ipfs/boxo/pull/1021
We let IpfsNode implmement the contentRouter.Client interface with the new
method. We use our WAN-DHT to get the closest peers.
Additionally, Routing V1 HTTP API is exposed by default which enables light clients in browsers to use Kubo Gateway as delegated routing backend
Co-authored-by: Marcin Rataj <lidel@lidel.org>