Bring splide and three.js into local build

```
    <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r68/three.min.js"></script>
    <script src="https://cdn.jsdelivr.net/npm/@splidejs/splide@latest/dist/js/splide.min.js"></script>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@splidejs/splide@latest/dist/css/splide.min.css">
```

These should be served from istio.io.

