[Sol->Yul] Implementing struct copying from calldata to storage

test/libsolidity/semanticTests/structs/calldata/calldata_struct_to_storage.sol

@@ -0,0 +1,21 @@
+pragma experimental ABIEncoderV2;
+
+contract C {
+    struct S {
+        uint256 a;
+        uint256 b;
+        bytes2 c;
+    }
+
+    S s;
+
+    function f(uint32 a, S calldata c, uint256 b) external returns (uint256, uint256, byte) {
+        s = c;
+        return (s.a, s.b, s.c[1]);
+    }
+}
+
+// ====
+// compileViaYul: true
+// ----
+// f(uint32, (uint256, uint256, bytes2), uint256): 1, 42, 23, "ab", 1 -> 42, 23, "b"