[Windows] Header/Footer re-add and removal issues in CollectionView

### Description

When the header/footer are added in CollectionView, the following issues were observed on Windows platform.

Windows: When toggling the Header/Footer button to the null state and then enabling it again, the header or footer content is not added back

Actual Behavior:
Windows - the header or footer content is not added back.

Expected Behavior:
On Windows: Header/Footer should be re-added.

### Steps to Reproduce

```
public partial class MainPage : ContentPage
{
private CollectionView _collectionView;
private Button _headerButton;
private Button _footerButton;

public MainPage()
{
//InitializeComponent();
var grid = new Grid
{
Margin = new Thickness(20),
RowDefinitions =
{
new RowDefinition { Height = GridLength.Auto },
new RowDefinition { Height = GridLength.Auto },
new RowDefinition { Height = GridLength.Star }
}
};

// Header Label
var headerLabel = new Label
{
Text = "Test for CollectionView empty view positioning",
AutomationId = "HeaderLabel",
};
Grid.SetRow(headerLabel, 0);
grid.Children.Add(headerLabel);

// Control buttons
var buttonGrid = new Grid
{
ColumnDefinitions =
{
new ColumnDefinition { Width = GridLength.Star },
new ColumnDefinition { Width = GridLength.Star }
},
Margin = new Thickness(0, 10)
};

var toggleHeaderButton = new Button
{
AutomationId = "ToggleHeaderButton",
Text = "Remove Header",
};
toggleHeaderButton.Clicked += OnToggleHeaderClicked;
Grid.SetColumn(toggleHeaderButton, 0);
buttonGrid.Children.Add(toggleHeaderButton);

var toggleFooterButton = new Button
{
AutomationId = "ToggleFooterButton",
Text = "Remove Footer",
};
toggleFooterButton.Clicked += OnToggleFooterClicked;
Grid.SetColumn(toggleFooterButton, 1);
buttonGrid.Children.Add(toggleFooterButton);

Grid.SetRow(buttonGrid, 1);
grid.Children.Add(buttonGrid);

// CollectionView
_collectionView = new CollectionView
{
AutomationId = "CollectionView",
ItemsSource = Array.Empty(), // empty array to trigger EmptyView
ItemTemplate = new DataTemplate(() =>
{
return new Label
{
TextColor = Colors.Black,
FontSize = 16,
// This binding works with string items
BindingContext = "{Binding .}"
};
})
};

// EmptyView
_collectionView.EmptyView = new Label
{
AutomationId = "EmptyViewLabel",
BackgroundColor = Color.FromArgb("#FFE40606"),
Text = "EmptyView: This should show when no data.",
};

// Initial header
_headerButton = new Button
{
AutomationId = "CollectionViewHeader",
BackgroundColor = Colors.LightBlue,
Text = "Header: Click me to verify EmptyView position",
};
_collectionView.Header = _headerButton;

// Initial footer (null)
_footerButton = new Button
{
AutomationId = "CollectionViewFooter",
BackgroundColor = Colors.LightCoral,
Text = "Footer: Click me to verify EmptyView position",
};
_collectionView.Footer = _footerButton

Grid.SetRow(_collectionView, 2);
grid.Children.Add(_collectionView);

// Set ContentPage content
Content = grid;
}

private void OnToggleHeaderClicked(object? sender, EventArgs e)
{
var button = (Button)sender!;

if (_collectionView.Header != null)
{
_collectionView.Header = null;
button.Text = "Add Header";
}
else
{
_collectionView.Header = _headerButton;
button.Text = "Remove Header";
}
}

private void OnToggleFooterClicked(object? sender, EventArgs e)
{
var button = (Button)sender!;

if (_collectionView.Footer != null)
{
_collectionView.Footer = null;
button.Text = "Add Footer";
}
else
{
_collectionView.Footer = _footerButton;
button.Text = "Remove Footer";
}
}
}
```

1.Paste the above code in Code behind
2. Toggle the header and footer button

### Link to public reproduction project repository

_No response_

### Version with bug

10.0.10

### Is this a regression from previous behavior?

No, this is something new

### Last version that worked well

Unknown/Other

### Affected platforms

Windows

### Affected platform versions

_No response_

### Did you find any workaround?

_No response_

### Relevant log output

```shell

```

Start with the provided MainPage code-behind reproduction on Windows and run the header and footer toggle actions in CollectionView. Observe the transitions in OnToggleHeaderClicked and OnToggleFooterClicked, then verify that assigning the saved controls after null restores both elements as expected.

Written by the indexing model from the issue text.