Represent IPFS Cluster in WebUI/Desktop

[olizilla]

ETA April 2020: Let's also consider the "pinning buddy system" thoughts originally in https://github.com/ipfs/ipfs-gui/issues/36 as one way to introduce Cluster concepts.

@hsanjuan made the good point that the IPFS Web UI could usefully show info about IPFS Cluster nodes if the api is available.

As we discussed about having a Cluster tab in the IPFS web UI, here are some pointers and thoughts.

• Every cluster peer exposes their own REST API endpoint (at tcp/9094 by default)
• GET /id shows Cluster peer information
• GET /peers gives an array of [/id] for every cluster peer
• API docs: https://cluster.ipfs.io/developer/api/
• Someone wrote a cluster api client already (not sure if it's complete): https://github.com/te0d/js-ipfs-cluster-api
• Regarding response formats:
  • /id /peers return https://godoc.org/github.com/ipfs/ipfs-cluster/api#IDSerial
  • /pins returns [] of https://godoc.org/github.com/ipfs/ipfs-cluster/api#PinInfoSerial
  • /allocations returns [] of https://godoc.org/github.com/ipfs/ipfs-cluster/api#PinSerial

Things we need

• [ ] Support CORS Headers in Cluster for browsers to be happy showing stuff from here.
• [ ] See my list of peers with their names and IDs (or a fancy diagram).
• [ ] Display the pin statuses (/pins), filter, sort them etc. CIDs would have links to the IPLD explorer.

...and more input!

• What extra info does cluster expose that we'd benefit from visualising?
• What blockers are there to re-using the new Web UI with cluster today?