feat: Add TokenTransfer class to Curve

- This needed to be in Curve 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

@@ -108,7 +108,7 @@ contract TychoRouterTestSetup is Constants, Permit2TestHelper {
         );
         balancerv2Executor = new BalancerV2Executor();
         ekuboExecutor = new EkuboExecutor(ekuboCore);
-        curveExecutor = new CurveExecutor(ETH_ADDR_FOR_CURVE);
+        curveExecutor = new CurveExecutor(ETH_ADDR_FOR_CURVE, PERMIT2_ADDRESS);
 
         address[] memory executors = new address[](7);
         executors[0] = address(usv2Executor);