* Unite all reachability stores
* Upgrade script
* Fix tests
* Add UpdateReindexRoot to RebuildReachability
* Use dbTx when deleting reachability stores
* Use ghostdagDataWithoutPrunedBlocks when rebuilding reachability
* Use next tree ancestor wherever possible and avoid finality point search if the block is too close to pruning point
* Address the boundary case where the pruning point becomes the finality point
* some minor fixes
* Remove RebuildReachability and use manual syncing between old and new consensus for migration
* Remove sanity test (it failed when tips where not in the same order)
Co-authored-by: msutton <mikisiton2@gmail.com>
