V1 breaking changes

[InesaFitsner]

List of breaking changes in V1:

• Alignment: will have to use ft.Alignment.center(); ft.alignment.center will not work
• Control: key renamed to scroll_key
• ScrollableControl: on_scroll_interval renamed to scroll_interval
• Animation: instead of ft.animation.Animation use ft.Animation
• Tabs: instead of text: OptionalString and tab_content: Optional[Control] use label: Optional[StrOrControl])
• Pagelet: bottom_app_bar renamed to bottom_appbar
• page.client_storage changed to page.shared_preferences.
• Dialogs: page.show_dialog(dialog_name) instead of page.open(dialog_name); `page.pop_dialog() to close dialog
• NavigationDrawer: position property instead of page.drawer and page.end_drawer
• All buttons: no text property, use content instead
• NavigationRailDesctination: no label_content property, use label instead
• SafeArea.left, .top, .right, .bottom to SafeArea.avoid_intrusions_left, .avoid_intrusions_top, .avoid_intrusions_right, .avoid_intrusions_bottom.
• Badge: use label instead of text
• Padding, Margin: should have named, not positional arguments. For example, instead of ft.Padding.symmetric(0, 10) should be ft.Padding(vertical = 0, horizontal = 10)
• SegmentedButton: selected: List[str] instead of Optional[Set]. Example: selected=["1", "4"] instead of selected={"1", "4"}. TODO: support sets in flet V1
• CupertinoActionSheetAction, CupertinoDialogAction, CupertinoContextMenuAction: default instead of is_default_action; destructive instead of is_destructive_action
• ft.app(target=main) should be changed to ft.run(main) or ft.run(main=main).
• FilePicker is a service now and must be added to page.services to work. Also, it provides only async methods to open dialogs which return results right away -no "on_result" event anymore.
• DragTarget.on_will_accept is of DragWillAcceptEvent type with accept: bool field. Use e.accept instead of e.data. DragTarget.on_leave is of DragTargetLeaveEvent type with src_id field. Use e.src_id instead of e.data.