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?

Cargo.lock

@@ -2518,14 +2518,16 @@ version = "0.1.0"
 dependencies = [
  "derivative",
  "either",
+ "enr",
  "eth2_keystore",
  "ethereum_serde_utils",
  "ethereum_ssz",
  "ethereum_ssz_derive",
  "futures",
  "futures-util",
- "lighthouse_network",
+ "libp2p-identity",
  "mediatype",
+ "multiaddr",
  "pretty_reqwest_error",
  "proto_array",
  "reqwest",
@@ -2535,7 +2537,6 @@ dependencies = [
  "serde_json",
  "slashing_protection",
  "ssz_types",
- "store",
  "tokio",
  "types",
  "zeroize",
@@ -2980,7 +2981,6 @@ dependencies = [
  "builder_client",
  "bytes",
  "eth2",
- "eth2_network_config",
  "ethereum_serde_utils",
  "ethereum_ssz",
  "ethers-core",
@@ -5309,6 +5309,7 @@ dependencies = [
  "dirs",
  "discv5",
  "either",
+ "eth2",
  "ethereum_ssz",
  "ethereum_ssz_derive",
  "fnv",
@@ -9486,7 +9487,6 @@ name = "validator_test_rig"
 version = "0.1.0"
 dependencies = [
  "eth2",
- "logging",
  "mockito",
  "regex",
  "sensitive_url",
@@ -9583,7 +9583,6 @@ dependencies = [
  "bytes",
  "eth2",
  "headers",
- "metrics",
  "safe_arith",
  "serde",
  "serde_array_query",