[Sol->Yul] Implementing conversion of struct to struct pointer.

Co-authored-by: Daniel Kirchner <daniel@ekpyron.org>

test/libsolidity/semanticTests/structs/struct_reference.sol

@@ -18,6 +18,8 @@ contract test {
         inner.recursive[0].z = inner.recursive[1].z + 1;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // check() -> false
 // set() ->