feat(substreams): add substreams for Uniswap v2 and v3

substreams/crates/substreams-helper/src/storage_change.rs

@@ -0,0 +1,14 @@
+use substreams_ethereum::pb::eth::v2::StorageChange;
+
+pub trait StorageChangesFilter {
+    fn filter_by_address(&self, contract_addr: &[u8; 20]) -> Vec<&StorageChange>;
+}
+
+impl StorageChangesFilter for Vec<StorageChange> {
+    fn filter_by_address(&self, contract_addr: &[u8; 20]) -> Vec<&StorageChange> {
+        return self
+            .iter()
+            .filter(|change| change.address == contract_addr)
+            .collect();
+    }
+}