## Issue Addressed
- Resolves#1080
## Proposed Changes
- Call `update_pubkey_cache` only in the `build_all_caches` method and `get_validator_index` method.
## Additional Info
This does reduce the number of places the cache is updated, making it simpler. But the `get_validator_index` method is used a couple times when we are iterating through the entire validator registry (or set of active validators). Before, we would only call `update_pubkey_cache` once before iterating through all validators. So I'm not _totally_ sure this change is worth it.
## 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
* Update state processing for v0.12
* Fix EF test runners for v0.12
* Fix some tests
* Fix broken attestation verification test
* More test fixes
* Fix typo found in review
