fix(api): fix log timestamp format (matter-labs#2407)

## What ❔

timestamp should be (de)serialized as QUANTITY (hex string)

## Why ❔

Follow proposal spec

## Checklist

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- [ ] PR title corresponds to the body of PR (we generate changelog
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- [ ] Tests for the changes have been added / updated.
- [ ] Documentation comments have been added / updated.
- [ ] Code has been formatted via `zk fmt` and `zk lint`.

core/lib/basic_types/src/web3/mod.rs

@@ -329,7 +329,7 @@ pub struct Log {
     pub removed: Option<bool>,
     /// L2 block timestamp
     #[serde(rename = "blockTimestamp")]
-    pub block_timestamp: Option<i64>,
+    pub block_timestamp: Option<U64>,
 }
 
 impl Log {

core/lib/dal/src/models/storage_event.rs

@@ -48,7 +48,7 @@ impl From<StorageWeb3Log> for api::Log {
             transaction_log_index: Some(U256::from(log.event_index_in_tx as u32)),
             log_type: None,
             removed: Some(false),
-            block_timestamp: log.block_timestamp,
+            block_timestamp: log.block_timestamp.map(|t| (t as u64).into()),
         }
     }
 }

core/lib/dal/src/transactions_web3_dal.rs

@@ -123,7 +123,7 @@ impl TransactionsWeb3Dal<'_, '_> {
                     .map(|mut log| {
                         log.block_hash = Some(receipt.block_hash);
                         log.l1_batch_number = receipt.l1_batch_number;
-                        log.block_timestamp = block_timestamp;
+                        log.block_timestamp = block_timestamp.map(|t| (t as u64).into());
                         log
                     })
                     .collect();

core/lib/types/src/api/mod.rs

@@ -445,7 +445,7 @@ pub struct Log {
     pub removed: Option<bool>,
     /// L2 block timestamp
     #[serde(rename = "blockTimestamp")]
-    pub block_timestamp: Option<i64>,
+    pub block_timestamp: Option<U64>,
 }
 
 impl Log {