feat: Support Curve ETH

Curve pools use a different address from ETH (native token)

- Pass Chain into the SwapEncoderBuilder and SwapEncoder
- Add native_token_curve_address and native_token_address to CurveSwapEncoder
- Added integration test for this curve case

--- don't change below this line ---
ENG-4306 Took 1 hour 4 minutes


Took 11 seconds

foundry/test/Constants.sol

@@ -30,7 +30,8 @@ contract Constants is Test, BaseConstants {
     address UNPAUSER = makeAddr("unpauser");
 
     // Assets
-    address ETH_ADDR = address(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
+    address ETH_ADDR_FOR_CURVE =
+        address(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
     address WETH_ADDR = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);
     address DAI_ADDR = address(0x6B175474E89094C44Da98b954EedeAC495271d0F);
     address BAL_ADDR = address(0xba100000625a3754423978a60c9317c58a424e3D);