Add Better Docs/Samples for Animations component

We should have the following for the Animations package:

```[tasklist]
### Tasks
- [ ] Port existing AnimationSet/ImplicitAnimationSet/AnimationBuilder/Connected/ItemsReorderAnimations docs
- [ ] Better introductory guidance on getting started with Animations in general (central 'Animations' page) - how are these things connected, what types of animations (implicit, explicit, connected, etc...)
- [ ] Ensure there's some basic samples on simple animation sets (Explicit) - no extra frills
- [ ] Bring over existing Connected Animations sample
- [ ] Bring over existing ItemsReorderAnimation sample
- [ ] Bring over Scale animation sample
```

Comienza revisando el paquete Animations y toda la documentación y los ejemplos existentes de AnimationSet, ImplicitAnimationSet, AnimationBuilder, Connected e ItemsReorderAnimations. Organiza una introducción centralizada, traslada los ejemplos enumerados y confirma que todas las tareas de la lista de comprobación estén cubiertas.

Escrito por el modelo de indexación a partir del texto del issue.