[parent] ipni/offer protocol

[hannahhoward]

Implement part of https://github.com/web3-storage/RFC/blob/main/rfc/ipni-w3c.md

For now, we will ship content claims indexing from the client, but then trigger the rest of the claim publishing with existing CARPARK indexes and ipni publishing flows

• Support IPNI+Carpark indexing from the client #24
• Server side triggering of IPNI publishing #55

[reidlw]

This is blocked on the need to make some decisions around read/write path, and those meetings are happening today.

[alanshaw]

Completed in:

• feat: generate sharded DAG index on client and invoke w index/add w3up#1451
• feat!: add index/add handler w3up#1421
• feat: add dependencies for index/add invocations w3infra#363