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

foundry/test/TychoRouterTestSetup.sol

@@ -106,7 +106,7 @@ contract TychoRouterTestSetup is Constants, Permit2TestHelper {
         pancakev3Executor = new UniswapV3Executor(
             factoryPancakeV3, initCodePancakeV3, PERMIT2_ADDRESS
         );
-        balancerv2Executor = new BalancerV2Executor();
+        balancerv2Executor = new BalancerV2Executor(PERMIT2_ADDRESS);
         ekuboExecutor = new EkuboExecutor(ekuboCore);
         curveExecutor = new CurveExecutor(ETH_ADDR_FOR_CURVE, PERMIT2_ADDRESS);