feat: balancer v3 gateway fixes (#153)

* feat: balancer v3 router gateway

* fix: change safeApprove to forceApprove in balancer gateway

* fix: change balancer gateway to handle fee on transfer tokens

contracts/helpers/balancer/BalancerV3RouterGateway.sol

@@ -37,8 +37,13 @@ contract BalancerV3RouterGateway is IBalancerV3Router {
         bool wethIsEth,
         bytes calldata userData
     ) external returns (uint256 amountOut) {
+        uint256 balanceBefore = tokenIn.balanceOf(address(this));
+
         tokenIn.safeTransferFrom(msg.sender, address(this), exactAmountIn);
-        tokenIn.safeApprove(permit2, exactAmountIn);
+
+        exactAmountIn = tokenIn.balanceOf(address(this)) - balanceBefore;
+
+        tokenIn.forceApprove(permit2, exactAmountIn);
         IPermit2(permit2).approve(address(tokenIn), balancerV3Router, uint160(exactAmountIn), uint48(block.timestamp));
 
         IBalancerV3Router(balancerV3Router).swapSingleTokenExactIn(
@@ -47,7 +52,7 @@ contract BalancerV3RouterGateway is IBalancerV3Router {
 
         amountOut = _transferBalance(tokenOut);
 
-        tokenIn.safeApprove(permit2, 1);
+        tokenIn.forceApprove(permit2, 1);
 
         return amountOut;
     }