[New Library] AndroidX RecyclerView extensions

[AndroidX RecyclerView](https://developer.android.com/jetpack/androidx/releases/recyclerviw) currently has no Kotlin extensions AFAICT.

## API suggestions

* [x] Kotlin properties for getters/setters that don't automatically map to their property equivalent (see [issue 204918397 on Google's IssueTracker](https://issuetracker.google.com/issues/204918397))
* [ ] `ItemTouchHelper` methods for:
* [ ] Attaching a helper to a `RecyclerView` (this already exists from `ItemTouchHelper` -> `RecyclerView` via [`attachToRecyclerView`](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/ItemTouchHelper#attachToRecyclerView(androidx.recyclerview.widget.RecyclerView)), but there's no equivalent for the other direction - `RecyclerView` -> `ItemTouchHelper`)
* [ ] Creating a [`SimpleCallback`](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/ItemTouchHelper.SimpleCallback)
* [ ] Value class for specifying drag/swipe directions
* [x] Convenience method to create a [`DiffUtil.ItemCallback`](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/DiffUtil.ItemCallback) with lambdas