[Sol->Yul] Implementing push for nested storage arrays and storage arrays of structs.

test/libsolidity/semanticTests/getters/mapping_array_struct.sol

@@ -16,6 +16,8 @@ contract C {
         n[1][1].b = 10;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // m(uint256,uint256): 0, 0 -> FAILURE
 // m(uint256,uint256): 1, 0 -> 1, 2