feat: Add TokenTransfer class to BalancerV2

- This needed to be in BalancerV2 so that the executor can also take care of transfers from the user into the tycho router, to avoid having transfer actions mixed between the router and executors

src/encoding/evm/swap_encoder/swap_encoders.rs

@@ -281,6 +281,7 @@ impl SwapEncoder for BalancerV2SwapEncoder {
             component_id,
             bytes_to_address(&encoding_context.receiver)?,
             approval_needed,
+            (encoding_context.transfer_type as u8).to_be_bytes(),
         );
         Ok(args.abi_encode_packed())
     }
@@ -703,7 +704,7 @@ mod tests {
             router_address: Some(Bytes::zero(20)),
             group_token_in: token_in.clone(),
             group_token_out: token_out.clone(),
-            transfer_type: TransferType::Transfer,
+            transfer_type: TransferType::None,
         };
         let encoder = BalancerV2SwapEncoder::new(
             String::from("0x543778987b293C7E8Cf0722BB2e935ba6f4068D4"),
@@ -731,7 +732,9 @@ mod tests {
                 // receiver
                 "1d96f2f6bef1202e4ce1ff6dad0c2cb002861d3e",
                 // approval needed
-                "01"
+                "01",
+                // transfer type
+                "05"
             ))
         );
     }