feat: track block fetch bytes in flight

[Gipphe]

Track bytes in flight for current block fetch requests on a per-node basis and limit the bytes in flight accordingly. This strategy is adopted from the cardano-node's own implementation of watermarks and in-flight byte tracking for BlockFetch.

Depends on #200

[dpulls]

🎉 All dependencies have been resolved !

[prednaz]

Suggested change

pure ()

[prednaz]

waiting like this would only make sense if this mini protocol was executed concurrently in multiple threads. else, who are we waiting for? this mini protocol is not executed concurrently in multiple threads, is it?

[cgeorgii]

This is a valid point. The current block fetch client is not pipelined (unlike ChainSync), so I think this flow control mechanism is never going to trigger.

@Gipphe either we pipeline the client or reevaluate whether this PR benefits us at all. I'm leaning toward the latter for now.

[cgeorgii]

@Gipphe while reviewing I changed a few things to improve readability and opened a pull request targeting this branch. Please check and merge into this, then I'll approve it.

[Gipphe]

There is no pipelined version of the BlockFetch client, so I'm not entirely sure how cardano-node parallelizes their block fetching. Since just upping the maxIngressQueueLimit helped this situation, and we don't end up blowing the new limit with concurrent block fetch requests, we'll shelve this PR for now as archived/feat/track-block-fetch-bytes-in-flight.