* Extract `OptimisticSyncFetcher` interface
* extract IsOptimistic
* fix tests
* more test fixes
* even more test fixes
Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>
Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>