decouple eth2 from store and lighthouse_network (#6680)

- #6452 (partially)


  Remove dependencies on `store` and `lighthouse_network`  from `eth2`. This was achieved as follows:

- depend on `enr` and `multiaddr` directly instead of using `lighthouse_network`'s reexports.
- make `lighthouse_network` responsible for converting between API and internal types.
- in two cases, remove complex internal types and use the generic `serde_json::Value` instead - this is not ideal, but should be fine for now, as this affects two internal non-spec endpoints which are meant for debugging, unstable, and subject to change without notice anyway. Inspired by #6679. The alternative is to move all relevant types to `eth2` or `types` instead - what do you think?

beacon_node/lighthouse_network/Cargo.toml

@@ -13,6 +13,7 @@ directory = { workspace = true }
 dirs = { workspace = true }
 discv5 = { workspace = true }
 either = { workspace = true }
+eth2 = { workspace = true }
 ethereum_ssz = { workspace = true }
 ethereum_ssz_derive = { workspace = true }
 fnv = { workspace = true }