Finish the all_forks syncing code

[tomaka]

https://github.com/paritytech/smoldot/pull/329 provided some initial implementation. While it is working, it's full of todo!()s and unbounded containers. It needs to be finished.

[tomaka]

cc https://github.com/paritytech/smoldot/pull/755

[tomaka]

To do:

• [x] Remove uninteresting blocks if the number of disjoint blocks is too high.
• [ ] Verify full blocks if full is true.
• [x] Refactor all.rs to have an API that matches the one in optimistic.rs and all_forks.rs.