AppBarButton / AppBarToggleButton Do Not Properly Use the Styling System for `Foreground`

[robloo]

Describe the bug

I see code such as the following:

Avalonia/src/Avalonia.Controls/CommandBar/AppBarToggleButton.cs

Lines 108 to 118 in 093976c

	private void UpdateIconForeground()
	{
	if (Icon is IconElement icon)
	{
	var fg = Foreground;
	if (fg != null)
	icon.SetValue(ForegroundProperty, fg);
	else
	icon.ClearValue(ForegroundProperty);
	}

This is a code smell and indicates something is incorrect with the way icons are being handled. Most of it comes from an incomplete IconElement implementation in Avalonia itself.

To Reproduce

See code:

Avalonia/src/Avalonia.Controls/CommandBar/AppBarButton.cs

Lines 106 to 117 in 093976c

	private void UpdateIconForeground()
	{
	if (Icon is IconElement icon)
	{
	var fg = Foreground;
	if (fg != null)
	icon.SetValue(ForegroundProperty, fg);
	else
	icon.ClearValue(ForegroundProperty);
	}
	}

Avalonia/src/Avalonia.Controls/CommandBar/AppBarToggleButton.cs

Lines 108 to 118 in 093976c

	private void UpdateIconForeground()
	{
	if (Icon is IconElement icon)
	{
	var fg = Foreground;
	if (fg != null)
	icon.SetValue(ForegroundProperty, fg);
	else
	icon.ClearValue(ForegroundProperty);
	}

Expected behavior

Foreground should be properly inherited without code-behind and be fully integrated with the Avalonia styling system.

Avalonia version

12.0 rc1

OS

No response

Additional context

No response