qt: fix extremely frustrating resize behavior in the home page

This fixes, to considerable extent, extremely frustrating resize behavior in the home page. Particularly observed when adjusting the width of the play queue pane, or the window width.

Currently the view models emit model reset signal as soon as the limit changes. This causes the views to re-load all items, which is not an acceptable behavior.

I wanted to use a screen-related constant for the maximum limits (similar to what we are doing in the player view to determine the cover art's maximum size), but I have not found such information provided by ExpandGridItemView.