[A11y] Add SemanticProperties.Description to the Toolbar Icon

[tj-devel709]

Description of Change

In the this issue: #26816, our A11y folks pointed out that Toolbar.Items with IconImageSource set do not properly have a "Label" in the accessibility inspector on Mac. This is important because that label allows the VoiceControl and VoiceOver to work properly for that button.

In the examples below you can see the accessibility inspector on the right with the label set on the After and not the Before.

    <ContentPage.ToolbarItems>
        <ToolbarItem
            Command="{Binding GroceriesCommand}"
            Order="Primary"
            Priority="0"
            IconImageSource="groceries.png"
            SemanticProperties.Description="Groceries" />
    </ContentPage.ToolbarItems>

Before:

After:

Issues Fixed

Partially resolves: #26816

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Comments suppressed due to low confidence (1)

src/Controls/src/Core/Compatibility/iOS/Extensions/AccessibilityExtensions.cs:90

• Ensure that the new behavior introduced by SemanticProperties.GetDescription is covered by tests.

Control.AccessibilityLabel = SemanticProperties.GetDescription(Element) ?? (string)Element.GetValue(AutomationProperties.NameProperty) ?? _defaultAccessibilityLabel;

[PureWeen]

I'm thinking we should fix all of the methods in here to route the UpdateSemantics implementations.

		public static string SetAccessibilityLabel(this NativeView Control, Element Element, string _defaultAccessibilityLabel = null)
		{
			if (Element is IView view && view.Semantics != null)
			{
				Control.UpdateSemantics(view);
				return String.Empty;
			}

And then create an issue/comment to obsolete this code in NET10