Feature: allow arrays in .slint to use `.contains()`

[flukejones]

This would be immensely valuable for me with some current work both in personal project and at work. It would allow for some conditional elements in .slint without having to manually manage it, or use a for loop where that might be overkill..

[ogoffart]

Similar to #1328 we could have
some_model.any(x => {x == 42})

[dorukotiv]

I think this feature request should be prioritized if possible.

[ivxvm]

A nice feature to have, my current workaround is to manually loop through array and check every element for equality with target value. This is not always applicable though.