feat: (WIP) Support selection of transfer into router

- For protocols like Balancer and Curve, which expect funds to be in the router at the time of swap, we must support also transferring funds from the user into the router. Doing this in the router would mean we are dealing with transfers in two different places: in the router main methods and in the executors. To avoid this, we are now performing transfers just in the executors, and two transfer types have been added to support transfers into the router.

TODO:
- Add this for Balancer and Curve (only added for USV4 atm).
- TODO consider renaming TRANSFER_FROM and TRANSFER_PERMIT2 to include "pool" in the name

foundry/src/executors/UniswapV4Executor.sol

@@ -17,10 +17,11 @@ import {Actions} from "@uniswap/v4-periphery/src/libraries/Actions.sol";
 import {IV4Router} from "@uniswap/v4-periphery/src/interfaces/IV4Router.sol";
 import {PathKey} from "@uniswap/v4-periphery/src/libraries/PathKey.sol";
 import {ICallback} from "@interfaces/ICallback.sol";
+import {TokenTransfer} from "./TokenTransfer.sol";
 
 error UniswapV4Executor__InvalidDataLength();
 
-contract UniswapV4Executor is IExecutor, V4Router, ICallback {
+contract UniswapV4Executor is IExecutor, V4Router, ICallback, TokenTransfer {
     using SafeERC20 for IERC20;
     using CurrencyLibrary for Currency;
 
@@ -30,7 +31,10 @@ contract UniswapV4Executor is IExecutor, V4Router, ICallback {
         int24 tickSpacing;
     }
 
-    constructor(IPoolManager _poolManager) V4Router(_poolManager) {}
+    constructor(IPoolManager _poolManager, address _permit2)
+        V4Router(_poolManager)
+        TokenTransfer(_permit2)
+    {}
 
     function swap(uint256 amountIn, bytes calldata data)
         external
@@ -41,9 +45,19 @@ contract UniswapV4Executor is IExecutor, V4Router, ICallback {
             address tokenIn,
             address tokenOut,
             bool zeroForOne,
+            TransferType transferType,
             UniswapV4Executor.UniswapV4Pool[] memory pools
         ) = _decodeData(data);
 
+        // TODO move this into callback when we implement callback transfer type support
+        _transfer(
+            tokenIn,
+            msg.sender,
+            address(this), // irrelevant attribute
+            amountIn,
+            transferType
+        );
+
         bytes memory swapData;
         if (pools.length == 1) {
             PoolKey memory key = PoolKey({
@@ -138,6 +152,7 @@ contract UniswapV4Executor is IExecutor, V4Router, ICallback {
             address tokenIn,
             address tokenOut,
             bool zeroForOne,
+            TransferType transferType,
             UniswapV4Pool[] memory pools
         )
     {
@@ -148,10 +163,11 @@ contract UniswapV4Executor is IExecutor, V4Router, ICallback {
         tokenIn = address(bytes20(data[0:20]));
         tokenOut = address(bytes20(data[20:40]));
         zeroForOne = (data[40] != 0);
+        transferType = TransferType(uint8(data[41]));
 
-        uint256 poolsLength = (data.length - 41) / 26; // 26 bytes per pool object
+        uint256 poolsLength = (data.length - 42) / 26; // 26 bytes per pool object
         pools = new UniswapV4Pool[](poolsLength);
-        bytes memory poolsData = data[41:];
+        bytes memory poolsData = data[42:];
         uint256 offset = 0;
         for (uint256 i = 0; i < poolsLength; i++) {
             address intermediaryToken;