tests(contracts): add new test contract for struct repacker

Signed-off-by: Luca Georges Francois <luca@quartz.technology>

Author: 0xpanoramix

tests/contracts/StructsToRepack.sol

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: UNLICENSED
+
+pragma solidity ^0.8.15;
+
+struct SimpleStruct {
+    uint128 a;
+    uint256 b;
+    uint128 c;
+}