## Proposed Changes
Add several metrics for the number of attestations in the op pool. These give us a way to observe the number of valid, non-trivial attestations during block packing rather than just the size of the entire op pool.
## 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>
## Proposed Changes
Use two instances of max cover when packing attestations into blocks: one for the previous epoch, and one for the current epoch. This reduces the amount of computation done by roughly half due to the `O(n^2)` running time of max cover (`2 * (n/2)^2 = n^2/2`). This should help alleviate some load on block proposal, particularly on Prater.
