feat(mempool): implement remove from nonce for account transaction index

crates/mempool/src/transaction_pool.rs

@@ -104,4 +104,27 @@ impl AccountTransactionIndex {
     fn get(&self, address: ContractAddress, nonce: Nonce) -> Option<&TransactionReference> {
         self.0.get(&address)?.get(&nonce)
     }
+
+    fn _remove_txs_up_to_nonce(
+        &mut self,
+        address: ContractAddress,
+        nonce: Nonce,
+    ) -> Vec<TransactionReference> {
+        let Some(btree_map) = self.0.get_mut(&address) else {
+            return Vec::default();
+        };
+
+        let mut txs: Vec<TransactionReference> = Vec::new();
+        let nonces_to_remove: Vec<Nonce> = btree_map.range(..=nonce).map(|(&n, _)| n).collect();
+        for n in nonces_to_remove {
+            txs.push(btree_map.remove(&n).expect("Failed to remove nonce from BTreeMap"));
+        }
+
+        // Remove the entry from the HashMap if the BTreeMap is empty
+        if btree_map.is_empty() {
+            self.0.remove(&address);
+        }
+
+        txs
+    }
 }