This tracks the work for handling IPNI announcements in the "PDP node w/ mkv1" branch for all the CIDs within a PDP piece.

Notes:

• This is stopgap work until FS can switch to mkv2, which already has this functionality (as mkv2 is what will ultimate be merged to master).
• This is intended to be a first check-in point, that will be followed up in FS: Optional indexing of PDP pieces based on metadata #625 where IPFS CID indexing is controlled by withIPFSIndexing indexing. For now we can do the naive thing of advertising of all CIDs.
• For M3 we only care about "IPFS CIDs". We don't need to care about the Piece CID (CommP v2).
• This is just what Curio does already for porep and it's just part of wiring it up without adding on additional requirements to get IPNI for PDP.
• Piece publishing to IPNI is not in scope here because it's also new to Curio, there isn't a workflow for this (other than probably mkv2), and because it's not critical for us for FS M3. it might be low cost for IPNI but not low cost for hooking it up in Curio. If this is desired, a followup issue can be created for this.