Split common crates out into their own repos (#3890)

## Proposed Changes

Split out several crates which now exist in separate repos under `sigp`.

- [`ssz` and `ssz_derive`](https://github.com/sigp/ethereum_ssz)
- [`tree_hash` and `tree_hash_derive`](https://github.com/sigp/tree_hash)
- [`ethereum_hashing`](https://github.com/sigp/ethereum_hashing)
- [`ethereum_serde_utils`](https://github.com/sigp/ethereum_serde_utils)
- [`ssz_types`](https://github.com/sigp/ssz_types)

For the published crates see: https://crates.io/teams/github:sigp:crates-io?sort=recent-updates.

## Additional Info

- [x] Need to work out how to handle versioning. I was hoping to do 1.0 versions of several crates, but if they depend on `ethereum-types 0.x` that is not going to work. EDIT: decided to go with 0.5.x versions.
- [x] Need to port several changes from `tree-states`, `capella`, `eip4844` branches to the external repos.

beacon_node/execution_layer/src/test_utils/handle_rpc.rs

@@ -362,7 +362,7 @@ pub async fn handle_rpc<T: EthSpec>(
         ENGINE_GET_PAYLOAD_BODIES_BY_RANGE_V1 => {
             #[derive(Deserialize)]
             #[serde(transparent)]
-            struct Quantity(#[serde(with = "eth2_serde_utils::u64_hex_be")] pub u64);
+            struct Quantity(#[serde(with = "serde_utils::u64_hex_be")] pub u64);
 
             let start = get_param::<Quantity>(params, 0)
                 .map_err(|s| (s, BAD_PARAMS_ERROR_CODE))?