Context menu item submenu appearing and disappearing in infinite loop

[tpetruk]

Steps to Reproduce:

1. Simple ContextMenu with 2 levels of menu items, e.g.:

          <ContextMenu>
            <MenuItem Header="Item 1" />
            <MenuItem Header="Item 2">
              <MenuItem Header="Item 2.1" />
              <MenuItem Header="Item 2.2" />
            </MenuItem>
            <MenuItem Header="Item 3">
              <MenuItem Header="Item 3.1" />
              <MenuItem Header="Item 3.2" />
            </MenuItem>
          </ContextMenu>

2. Hover the mouse over a top-level item containing child items, keep it for a couple of seconds.

Actual Result:

A submenu keeps opening and closing in a loop:
https://user-images.githubusercontent.com/93399973/149335063-91430ffe-d780-4ca3-bb9f-e41ff503f202.mp4

Initial Investigation:
The problem seems to be in the MenuItems Template.
https://github.com/AvaloniaCommunity/Material.Avalonia/blob/dev/Material.Styles/MenuItem.xaml#L69
For the Popups of submenu IsLightDismissEnabled is set to true. The thing is that it doesn't need to be true because the top-level Popup has IsLightDismissEnabled=true and it is enough.
The light-dismiss layer seems to be causing a problem, not entirely sure why, but it is always false in the other MenuItem styles for Avalonia that I've seen.