[Shell,iOS,Android] Add accessibility features for navigation bar and toolbar items...

[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