Sqlite: Fix null handling

Most of it is only silencing a warning but one is fixing a faulty test. So
writing null values should now be working.

Change-Id: If702e1fc8176a9e0ae82a5589c719d567929202b
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/sqlite/sqlitebasestatement.cpp

@@ -214,6 +214,9 @@ void BaseStatement::bind(int index, const Value &value)
     case ValueType::String:
         bind(index, value.toStringView());
         break;
+    case ValueType::Null:
+        bind(index, NullValue{});
+        break;
     }
 }