Consolidate Beacon Clients

Currently we use a different beacon client from the optimism monorepo. It would be nice to consolidate efforts in to a single library.

The blob archiver uses [go-eth-2](https://github.com/attestantio/go-eth2-client) while the optimism monorepo has its own [implementation](https://github.com/ethereum-optimism/optimism/blob/develop/op-service/sources/l1_beacon_client.go).

This is due to `go-eth-2` supporting SSZ of blob types out of the box. It would be ideal to combine efforts by either:

1. Migrating the monorepo to `go-eth-2`
2. Adding SSZ support to the monorepo and migrating the blob-archiver to use the client there.

Compare the blob-archiver's use of go-eth-2 with optimism's op-service/sources/l1_beacon_client.go implementation. Start by checking how each client handles beacon data and SSZ blob types. Done means both projects use one agreed client library with the required SSZ support, and the blob archiver and monorepo migrations are complete.

Written by the indexing model from the issue text.