Implement new virtual API for the Combobox component (#2779)

* add `(Vue)` or `(React)` to playground header

* show amount of items in virtualized example

* improve calculating the active index

* disable strict mode

* update virtualized playground examples with preferred API

* optimize `calculateActiveIndex`

* implement new `virtual` API

* update changelog

Author: RobinMalfait

packages/@headlessui-react/CHANGELOG.md

@@ -21,7 +21,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Add `immediate` prop to `<Combobox />` for immediately opening the Combobox when the `input` receives focus ([#2686](https://github.com/tailwindlabs/headlessui/pull/2686))
-- Add `virtual` prop to `Combobox` component ([#2740](https://github.com/tailwindlabs/headlessui/pull/2740))
+- Add `virtual` prop to `Combobox` component ([#2779](https://github.com/tailwindlabs/headlessui/pull/2779))
 
 ## [1.7.17] - 2023-08-17