FastUI Support

### Proposal:

For batteries-detachable purposes, view.py should support responses from [FastUI](https://github.com/pydantic/FastUI). This will likely be similar to how ReactPy is implemented when #118 is done.

Basically:

```py
from view import new_app
from fastui import components as c

app = new_app()

@app.get("/")
def index():
    return c.Page(...)

app.run()
```