Make transactions in execution layer integration tests (#3320)

## Issue Addressed

Resolves #3159 

## Proposed Changes

Sends transactions to the EE before requesting for a payload in the `execution_integration_tests`. Made some changes to the integration tests in order to be able to sign and publish transactions to the EE:

1. `genesis.json` for both geth and nethermind was modified to include pre-funded accounts that we know private keys for 
2. Using the unauthenticated port again in order to make `eth_sendTransaction` and calls from the `personal` namespace to import keys

Also added a `fcu` call with `PayloadAttributes` before calling `getPayload` in order to give EEs sufficient time to pack transactions into the payload.

testing/execution_engine_integration/src/transactions.rs

@@ -0,0 +1,87 @@
+use deposit_contract::{encode_eth1_tx_data, BYTECODE, CONTRACT_DEPLOY_GAS, DEPOSIT_GAS};
+use ethers_core::types::{
+    transaction::{eip2718::TypedTransaction, eip2930::AccessList},
+    Address, Bytes, Eip1559TransactionRequest, TransactionRequest,
+};
+use types::{DepositData, EthSpec, Hash256, Keypair, Signature};
+
+/// Hardcoded deposit contract address based on sender address and nonce
+pub const DEPOSIT_CONTRACT_ADDRESS: &str = "64f43BEc7F86526686C931d65362bB8698872F90";
+
+#[derive(Debug)]
+pub enum Transaction {
+    Transfer(Address, Address),
+    TransferLegacy(Address, Address),
+    TransferAccessList(Address, Address),
+    DeployDepositContract(Address),
+    DepositDepositContract {
+        sender: Address,
+        deposit_contract_address: Address,
+    },
+}
+
+/// Get a list of transactions to publish to the execution layer.
+pub fn transactions<E: EthSpec>(account1: Address, account2: Address) -> Vec<TypedTransaction> {
+    vec![
+        Transaction::Transfer(account1, account2).transaction::<E>(),
+        Transaction::TransferLegacy(account1, account2).transaction::<E>(),
+        Transaction::TransferAccessList(account1, account2).transaction::<E>(),
+        Transaction::DeployDepositContract(account1).transaction::<E>(),
+        Transaction::DepositDepositContract {
+            sender: account1,
+            deposit_contract_address: ethers_core::types::Address::from_slice(
+                &hex::decode(&DEPOSIT_CONTRACT_ADDRESS).unwrap(),
+            ),
+        }
+        .transaction::<E>(),
+    ]
+}
+
+impl Transaction {
+    pub fn transaction<E: EthSpec>(&self) -> TypedTransaction {
+        match &self {
+            Self::TransferLegacy(from, to) => TransactionRequest::new()
+                .from(*from)
+                .to(*to)
+                .value(1)
+                .into(),
+            Self::Transfer(from, to) => Eip1559TransactionRequest::new()
+                .from(*from)
+                .to(*to)
+                .value(1)
+                .into(),
+            Self::TransferAccessList(from, to) => TransactionRequest::new()
+                .from(*from)
+                .to(*to)
+                .value(1)
+                .with_access_list(AccessList::default())
+                .into(),
+            Self::DeployDepositContract(addr) => TransactionRequest::new()
+                .from(*addr)
+                .data(Bytes::from(BYTECODE.to_vec()))
+                .gas(CONTRACT_DEPLOY_GAS)
+                .into(),
+            Self::DepositDepositContract {
+                sender,
+                deposit_contract_address,
+            } => {
+                let keypair = Keypair::random();
+
+                let mut deposit = DepositData {
+                    pubkey: keypair.pk.into(),
+                    withdrawal_credentials: Hash256::zero(),
+                    amount: 32_000_000_000,
+                    signature: Signature::empty().into(),
+                };
+
+                deposit.signature = deposit.create_signature(&keypair.sk, &E::default_spec());
+                TransactionRequest::new()
+                    .from(*sender)
+                    .to(*deposit_contract_address)
+                    .data(Bytes::from(encode_eth1_tx_data(&deposit).unwrap()))
+                    .gas(DEPOSIT_GAS)
+                    .into()
+            }
+        }
+    }
+}