Be able to define classes with annotations

This pull request implements xp-framework/rfc#276 and adds the ability to pass annotations to `ClassLoader::defineClass()` and `ClassLoader::defineInterface()`. Based on thekid/xp-framework@bff75652799c699a8fd2f3a2168c117228dd1c8c, this is targeted for XP:six:

```php
ClassLoader::defineClass('#[@webservice] com.example.ws.rest.OrderHandler', 'lang.Object', [], '{
  // code
}');
```