[Shell,iOS,Android] Add accessibility features for navigation bar and toolbar items (#5758) fixes #5132
* [Controls,Shell] Add automation properties to FlyoutIcon
* [iOS] Set accessibility properties from flyout icon on ShellPageRenderer
* [Android] Add accessibility features to Shell flyout icon
* [Android] Add accessibility to shell toolbar and button items
* [Controls] Add uitest for issue #5132
* [Controls] Fix uitest android
* [Controls] Use new types
* [UItests] Only run on iOS and Android
Co-Authored-By: rmarinho <me@ruimarinho.net>
* [Controls] Add scrollview to test page
* [Android] Set icon AutomationId using NavigationContentDescription
* [Android] Restore code on AutomationPropertiesProvider
* [Android] Set help text or AutomationID for toolbar navigation content description
* Update Xamarin.Forms.Platform.Android/Renderers/ShellToolbarTracker.cs