Provide a component instance capture in RouteView (aka new RouteView.Instance property)

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

_No response_

### Describe the solution you'd like

`DynamicComponent` already has the `Instance` property, enabling access to the rendered component instance.

Is there anything against having such feature in `RazorView` component as well?
Code modification proposal would be:
```csharp
// src/Components/Components/src/RouteView.cs
public class RouteView : IComponent
{

+ ///
+ /// Gets rendered component instance.
+ ///
+ public object? Instance { get; private set; }

// (...)

private void RenderPageWithParameters(RenderTreeBuilder builder)
{
builder.OpenComponent(0, RouteData.PageType);

// (...)

+ builder.AddComponentReferenceCapture(2, component => Instance = component);
builder.CloseComponent();
}
}

```

### Additional context

In my case, I need to access the rendered component instance after all parameters were set (for our centralized state preservation implementation).
Creating my own router is a possibility, but I'll need to fallback to reflection to mimic today's RouteView behavior (e.g.: the `QueryParameterValueSupplier` is internal and my approach will not be not future-safe).

If suggestion approved, I can provide a pull request.