ListView not recycling items if they are custom components

[hdeshev]

1. The ng ListView component creates ng views and caches them as list view item views properties.
2. The base list view implementation has some extra code that wraps ProxyViewContainer objects (user components render as those!) in an additional StackLayout.
3. That breaks the caching check and causes the ng component to always create a new item view instead of recycling the existing one.