Prior to this PR we realized that the RFC had been drafted with the assumption that chains would be ordered from best to worst in `NonFinalizedState`. This assumption was incorrect, since `BTreeSet` only ever orders values in ascending order. This discrepancy was noticed and fixed in the code, but there were still some inconsistencies that needed to be cleaned up.
This PR updates all the incorrect or confusing comments about chain ordering in the RFC and code.
Prior to this PR `memory_state` defined and implemented functionality for three different types, `Chain`, `NonFinalizedState`, and `QueuedBlocks`. Each of these components will need a fair number of unit tests, and I realized that as its currently organized it would be difficult to organize the tests or at a glance figure out which tests are testing which components.
This PR changes the organization of `memory_state` such that each component it exports is defined in its own module. In follow up PRs each module will get its own test module, which will focus exclusively on unit tests for the item defined there-in.
- [Tracking Issue](https://github.com/ZcashFoundation/zebra/issues/1250)
Jane Lusby
Jane Lusby
teor