Customizable Flyout or Flyout for MenuItem

## Summary
The ToolbarItem in Xamarin Forms is not really customizable, you cannot change background color without pain and does not really support svg icons and path data geometry. I hope this features will be added to MAUI Control. So that we can fully customize the look and show flyout at any position of screen. Here is the sample for UWP Xaml Flyout.

## Intended Use Case
```

```
Show to the specific position by finding the ui location.
```
private void iconDataGrid_RightTapped(object sender, RightTappedRoutedEventArgs e)
{
var data = (sender as FrameworkElement).DataContext;
if (data != null && data is PathIcon)
{
var tappedItem = (UIElement)e.OriginalSource;
var attachedFlyout = (Flyout)FlyoutBase.GetAttachedFlyout(this.rootGrid);
attachedFlyout.ShowAt(tappedItem, e.GetPosition(tappedItem));
}

}
```
Results

No repository files or tests are named. Start by reading the MAUI ToolbarItem and Flyout APIs, then compare the requested behavior with the provided UWP XAML and ShowAt example; done would require a defined customizable menu flyout with configurable appearance, SVG or path icons, and positioning support.

Written by the indexing model from the issue text.