[Catalyst] Adding and Removing ContextMenus currently does not work

[PureWeen]

Description

The code needs to be filled in for adding/removing Context Menus

• Windows it kind of works. If you test the controls sample it sometimes adds one sub menu item but then others don't get added
• Catalyst completely doesn't work

On catalyst I found that the issue is related to not disconnecting the handler before recreating the menu.

Workaround

You can pretty easily fix it by adding the following disconnect code

But after I did that the behavior of the ContextMenu on the WkWebView became more erratic

Depends on

• Can't add MenuFlyoutItem to MenuFlyoutSubItem at runtime microsoft/microsoft-ui-xaml#7797
• Workaround WinUI bug with adding/removing flyouts #14985

VS bug #1816116