## Issue Addressed
NA
## Proposed Changes
- Adds a `lighthouse account validator list` command, to list all known validators.
- Fixes the validator names; previously they were using a full path (e.g., `"/home/paul/.lighthouse/validators/0x8ce25415d078bdc83133758604578ba51707a55965eeca8982f44695db7432d6ff1c23529020a971faa68ab60baf3118"` but now we only use the final directory name (e.g., `0x8ce25415d078bdc83133758604578ba51707a55965eeca8982f44695db7432d6ff1c23529020a971faa68ab60baf3118`).
## 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
