Rust 1.54.0 lints (#2483)

## Issue Addressed

N/A

## Proposed Changes

- Removing a bunch of unnecessary references
- Updated `Error::VariantError` to `Error::Variant`
- There were additional enum variant lints that I ignored, because I thought our variant names were fine
- removed `MonitoredValidator`'s `pubkey` field, because I couldn't find it used anywhere. It looks like we just use the string version of the pubkey (the `id` field) if there is no index

## Additional Info



Co-authored-by: realbigsean <seananderson33@gmail.com>

crypto/bls/src/impls/fake_crypto.rs

@@ -146,7 +146,7 @@ impl TAggregateSignature<PublicKey, AggregatePublicKey, Signature> for Aggregate
     fn deserialize(bytes: &[u8]) -> Result<Self, Error> {
         let mut key = [0; SIGNATURE_BYTES_LEN];
 
-        key[..].copy_from_slice(&bytes);
+        key[..].copy_from_slice(bytes);
 
         Ok(Self(key))
     }