Implement Slashing Protection (#1116)

* Implement slashing protection

Roll-up of #588 with some conflicts resolved

* WIP improvements

* Require slot uniqueness for blocks (rather than epochs)
* Native DB support for Slot and Epoch
* Simplify surrounding/surrounded-by queries

* Implement unified slashing protection database

A single SQL database saves on open file descriptors.

* Make slashing protection concurrency safe.

Revive tests, add parallel tests.

* Some simplifications

* Auto-registration, test clean-ups

* More tests, clean-ups, hardening

* Fix comments in BLS

* Optimise bulk validator registration

* Delete outdated tests

* Use bundled SQLite in slashing protection

* Auto-register validators in simulation

* Use real signing_root in slashing protection

* Update book for --auto-register

* Refine log messages and help flags

* Correct typo in Cargo.toml authors

* Fix merge conflicts

* Safer error handling in sqlite slot/epoch

* Address review comments

* Add attestation test mutating block root

Co-authored-by: pscott <scottpiriou@gmail.com>

validator_client/src/block_service.rs

@@ -210,6 +210,11 @@ impl<T: SlotClock + 'static, E: EthSpec> BlockService<T, E> {
     async fn publish_block(self, slot: Slot, validator_pubkey: PublicKey) -> Result<(), String> {
         let log = &self.context.log;
 
+        let current_slot = self
+            .slot_clock
+            .now()
+            .ok_or_else(|| "Unable to determine current slot from clock".to_string())?;
+
         let randao_reveal = self
             .validator_store
             .randao_reveal(&validator_pubkey, slot.epoch(E::slots_per_epoch()))
@@ -225,7 +230,7 @@ impl<T: SlotClock + 'static, E: EthSpec> BlockService<T, E> {
 
         let signed_block = self
             .validator_store
-            .sign_block(&validator_pubkey, block)
+            .sign_block(&validator_pubkey, block, current_slot)
             .ok_or_else(|| "Unable to sign block".to_string())?;
 
         let publish_status = self