Memoize bytecode (#2918)

# Description
The newly added metrics show that filtering invalid signatures can be
quite slow. Since I don't see any low hanging fruit to speed up the
simulation code let's just at least memoize the bytecode we pass to the
simulation function since that never changes anyway.
This skips hex-decoding the contract bytecode on every simulation.

## How to test
existing e2e tests should continue to work

crates/contracts/src/storage_accessible.rs

@@ -13,6 +13,7 @@ use {
         },
         H160,
     },
+    std::sync::LazyLock,
 };
 
 /// Encode a call to a `StorageAccessible` `target` to execute `call` with the
@@ -27,20 +28,12 @@ pub fn call(target: H160, code: Bytes, call: Bytes) -> CallRequest {
         ethcontract::Bytes(call.0).into_token(),
     ]);
 
+    // memoize value to skip hex-decodeing on every call
+    static BYTECODE: LazyLock<Vec<u8>> =
+        LazyLock::new(|| SimulateCode::raw_contract().bytecode.to_bytes().unwrap().0);
+
     CallRequest {
-        data: Some(
-            [
-                SimulateCode::raw_contract()
-                    .bytecode
-                    .to_bytes()
-                    .unwrap()
-                    .0
-                    .as_slice(),
-                &args,
-            ]
-            .concat()
-            .into(),
-        ),
+        data: Some([BYTECODE.as_slice(), &args].concat().into()),
         ..Default::default()
     }
 }

crates/shared/src/signature_validator/simulation.rs

@@ -11,6 +11,7 @@ use {
     ethrpc::Web3,
     futures::future,
     primitive_types::{H160, U256},
+    std::sync::LazyLock,
 };
 
 pub struct Validator {
@@ -33,13 +34,17 @@ impl Validator {
         &self,
         check: &SignatureCheck,
     ) -> Result<Simulation, SignatureValidationError> {
+        // memoize byte code to not hex-decode it on every call
+        static BYTECODE: LazyLock<web3::types::Bytes> =
+            LazyLock::new(|| contracts::bytecode!(contracts::support::Signatures));
+
         // We simulate the signature verification from the Settlement contract's
         // context. This allows us to check:
         // 1. How the pre-interactions would behave as part of the settlement
         // 2. Simulate the actual `isValidSignature` calls that would happen as part of
         //    a settlement
         let gas_used = contracts::storage_accessible::simulate(
-            contracts::bytecode!(contracts::support::Signatures),
+            BYTECODE.clone(),
             self.signatures.methods().validate(
                 (self.settlement, self.vault_relayer),
                 check.signer,