## Issue Addressed
NA
## Proposed Changes
- Refactor the `bls` crate to support multiple BLS "backends" (e.g., milagro, blst, etc).
- Removes some duplicate, unused code in `common/rest_types/src/validator.rs`.
- Removes the old "upgrade legacy keypairs" functionality (these were unencrypted keys that haven't been supported for a few testnets, no one should be using them anymore).
## Additional Info
Most of the files changed are just inconsequential changes to function names.
## TODO
- [x] Optimization levels
- [x] Infinity point: https://github.com/supranational/blst/issues/11
- [x] Ensure milagro *and* blst are tested via CI
- [x] What to do with unsafe code?
- [x] Test infinity point in signature sets
* 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* Delete outdated tests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>
