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.

validator_client/src/signing_method/web3signer.rs

@@ -54,9 +54,9 @@ pub enum Web3SignerObject<'a, T: EthSpec, Payload: AbstractExecPayload<T>> {
     Deposit {
         pubkey: PublicKeyBytes,
         withdrawal_credentials: Hash256,
-        #[serde(with = "eth2_serde_utils::quoted_u64")]
+        #[serde(with = "serde_utils::quoted_u64")]
         amount: u64,
-        #[serde(with = "eth2_serde_utils::bytes_4_hex")]
+        #[serde(with = "serde_utils::bytes_4_hex")]
         genesis_fork_version: [u8; 4],
     },
     RandaoReveal {