Integrate minijinja into aiscript-runtime as template engine

```jinja
// hello-page.jinja
{% if query.is_admin %}
<div> Hello, {query.name} (Admin)</div>
{% else %}
<div> Hello, {query.name}</div>
{% endif %}
```
```js

get /hello {
    query {
        name: str,
        is_admin: bool = false,
    }

    return render("hello-page.jinja", query);
}

```

- https://aiscript.dev/guide/contribution/roadmap#web-runtime
- https://github.com/mitsuhiko/minijinja