Extensible provider record storage/retrieval

[BigLep]

Done criteria: It is possible to instantiate an IpfsDHT server that is able to return to users provider records from alternative sources than just the datastore
Why important: This enables creating DHT server nodes with more sophisticated record management. In particular it will allow hydra nodes to store lots of addresses for peers without shoving them all into the libp2p host
Notes:

• This will get leveraged as part of Integrate delegated content routing client hydra-booster#140
• This stems from provider records being implicitly two parts:
  • A record of which peer has the data which is stored in the datastore for 24hrs
    • There is some extensibility here via the datastore, although it's not pretty.
  • The addresses for the given peer which the server happens to know about (they hang around for at least 30, previously 10, minutes https://github.com/libp2p/go-libp2p-core/blob/6e24b97081f344012f99421fab146910a63c6ee6/peerstore/peerstore.go#L31)
    • This is built in

      go-libp2p-kad-dht/handlers.go

      Line 325 in 5a8437e

      infos := pstore.PeerInfos(dht.peerstore, providers)

• This could be resolved by either adding more options to the ProviderManager or just having an interface for the provide manager that gets passed in as an option to the DHT. Note if taking the interface approach that we'll have to deprecate or remove

  go-libp2p-kad-dht/dht_options.go

  Line 244 in 5a8437e

  func ProvidersOptions(opts []providers.Option) Option {