Listview Persistence

This pull request adds a `data-persist` option for Listview items that will keep it visible for a few different Listview "modes":

1. __Autodividers__ - When a `data-role="list-divider"` also has the attribute `data-persist="true"` the "manually added" divider will NOT be removed, keeping it visible
2. __Filter__ - When a user enters criteria, the `data-persist="true"` list items/dividers will always stay visible
3. __Reveal Filter__ - When a reveal filter is initialized or the user enters criteria, the `data-persist="true"` list items/dividers will always stay visible

I've also included documentation changes to briefly mention this feature along with related test cases. If accepted, I'll also submit a API Pull Request to update documentation changes there.

Thank you for considering this feature. I'm more than willing to answer questions, make changes as needed.