Finish implementation of the happy-path CSJ prototype

[amesgen]

We now have a runnable MVP happy-path CSJ prototype. We should make sure that it supports a full sync to mainnet, in order to have confidence in the upcoming benchmarking experiments.

In particular, the new logic has non-trivial interactions with disconnecting peers (in particular when the dynamo disconnects), so we should make sure that we don't get random failures which would slow down future experiments.

[amesgen]

The happy-path CSJ prototype is in a sufficient state for benchmarking, i.e. its performance (even with very conservative parameters) is already in the same ballpark as 1.35.3, and it basic fault injection shows that it is sufficiently robust for local testing. The further work is tracked in IntersectMBO/ouroboros-consensus#557.