Nodes autolayout

**Is your feature request related to a problem? Please describe.**
At the moment, the developer shall define the nodes' coordinates to provide a valid schema, unfortunately this is not always ideal (and might result quite tedious for the developer) it would be nice to have an auto-layout feature .

**Describe the solution you'd like**

A prop to define if a Diagram is "autolayout"
```

```

And a function to programmatically re-organise the layout exported from the `useSchema` hook

```
const [schema, { autolayout }] = useSchema();
```