Bitswap cant currently handle other types of hashes

[whyrusleeping]

We recently in discussion about ipld discovered a bug in bitswap. When receiving a block, bitswap will check its hash and see if that hash is on its wantlist. This works right now because we only use one hash type, in the future when there are blocks with other types of identifiers floating around, we need to be able to check things with the correct function.

To do this, we need to assign a unique ID or index to each item in our wantlist, and attach each entries ID to it when sending out wantlists. Then, when someone sends us a block, they also send the ID of the wantlist entry they are fulfilling for us, allowing us to correctly identify what we've received.

This will be a 'breaking' protocol change for bitswap, but we can easily run both old and new code in compatibility mode for some time.

Depends on:

• Multistream Version Handling #3044

[whyrusleeping]

Was fixed in #3297