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* Delete outdated tests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>

eth2/utils/bls/src/fake_public_key.rs

@@ -41,8 +41,6 @@ impl FakePublicKey {
     }
 
     /// Returns the underlying point as compressed bytes.
-    ///
-    /// Identical to `self.as_uncompressed_bytes()`.
     pub fn as_bytes(&self) -> Vec<u8> {
         self.bytes.clone()
     }

eth2/utils/bls/src/public_key.rs

@@ -40,8 +40,6 @@ impl PublicKey {
     }
 
     /// Returns the underlying point as compressed bytes.
-    ///
-    /// Identical to `self.as_uncompressed_bytes()`.
     pub fn as_bytes(&self) -> Vec<u8> {
         self.as_raw().as_bytes()
     }