[State sync engine] Implement prioritization in bitswap

[synzhu]

This issue is tracked in the Bitswap repo here: ipfs/boxo#82

We would like to preserve the bandwidth of Execution Nodes, which are the only creators of new data. One way to do this is to implement some mechanism in bitswap for how we want to prioritize responding to requests for blocks.

Execution nodes should prioritize responding to requests for more recent blocks, to make sure that enough AN's download these blocks

[synzhu]

This is implemented here: ipfs/go-bitswap#535

All that's left to do is to implement the new Option in our usage of bitswap for execution nodes.