[Bug] Shell BackButtonBehaviour AutomationProperties aren't functioning as expected.

[jaisont07]

Description

Not able to customise the accessibility texts in shell backbutton. I need to change the back button to another image. So it is added in the iconoverride property.
And added automationproperties.name, helptext.. but the talk back responded as "OK button" in android and the image name in iOS.
Once text override is added, it will talk back that text in android.
But in ios, it is still the image name we added in iconoverride property.

 <Shell.BackButtonBehavior>

        <BackButtonBehavior

            AutomationProperties.Name="Back"
            AutomationProperties.IsInAccessibleTree="True"
            TextOverride="Back"
            Command="{Binding BackCommand}"
            IconOverride="back_arrow.png" />

    </Shell.BackButtonBehavior>

Steps to Reproduce

Expected Behavior

AutomationProperties.Name="required text"
It should talk back this text in both the platforms

Actual Behavior

"OK button" in Android,
"back arrow" iniOS

Basic Information

• Version with issue:
• Last known good version:
• Platform Target Frameworks:

Xamarin.Forms version 4.8.0.1821