MarkupExtension.ProvideValue doesnt have the proper target injected when used on attached property

[Xiaoy312]

Current behavior

public partial class ResponsiveExtension : MarkupExtension {
	protected override object? ProvideValue(IXamlServiceProvider serviceProvider) {
		var pvt = serviceProvider.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
		var target = pvt.TargetObject; // null

<Border Grid.Column="{utu:Responsive Narrowest=0, Narrow=1, Normal=0, Wide=1, Widest=1}" />

Expected behavior

^ should just work.

How to reproduce it (as minimally and precisely as possible)

See "##Current behavior"

Workaround

n/a

Works on UWP/WinUI

Yes

Environment

Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

Uno.WinUI@5.1.0-dev.486

Affected platforms

Build tasks

IDE

Visual Studio 2022

IDE version

n/a

Relevant plugins

n/a

Anything else we need to know?

// <Border Grid.Column="{utu:Responsive Narrowest=0, Narrow=1, Normal=0, Wide=1, Widest=1}" />
global::Microsoft.UI.Xaml.Controls.Grid.SetColumn(c11, (int)Microsoft.UI.Xaml.Markup.XamlBindingHelper.ConvertValue(
	typeof(int), 
	((global::Microsoft.UI.Xaml.Markup.IMarkupExtensionOverrides)new global::Uno.Toolkit.UI.ResponsiveExtension { Narrowest = @"0", Narrow = @"1", Normal = @"0", Wide = @"1", Widest = @"1" })
		.ProvideValue(global::Uno.UI.Helpers.MarkupHelper.CreateParserContext(
			null, // <============================= null here
			typeof(global::Microsoft.UI.Xaml.Controls.Grid), 
			"Column", 
			typeof(object)))));

// for comparison
// <StackPanel Orientation="{utu:Responsive Normal=Vertical, Wide=Horizontal}" />
c8.Orientation = (global::Microsoft.UI.Xaml.Controls.Orientation)Microsoft.UI.Xaml.Markup.XamlBindingHelper.ConvertValue(
	typeof(global::Microsoft.UI.Xaml.Controls.Orientation), 
	((global::Microsoft.UI.Xaml.Markup.IMarkupExtensionOverrides)new global::Uno.Toolkit.UI.ResponsiveExtension { Normal = @"Vertical", Wide = @"Horizontal" })
		.ProvideValue(global::Uno.UI.Helpers.MarkupHelper.CreateParserContext(
			c8, 
			typeof(global::Microsoft.UI.Xaml.Controls.StackPanel), 
			"Orientation", 
			typeof(object))));