* Move bank drop to AccountsBackgroundService
* Send to ABS on drop instead, protects against other places banks are dropped
* Fix Abi
* test
Co-authored-by: Carl Lin <carl@solana.com>
* Add service to track the most recent optimistically confirmed bank
* Plumb service into ClusterInfoVoteListener and ReplayStage
* Clean up test
* Use OptimisticallyConfirmedBank in RPC
* Remove superfluous notifications from RpcSubscriptions
* Use crossbeam to avoid mpsc recv_timeout panic
* Review comments
* Remove superfluous last_checked_slots, but pass in OptimisticallyConfirmedBank for complete correctness