SceneTransitionLayout now supports the nestedScroll API

The SceneTransitionLayout now supports the NestedScroll API, which
allows to interact with its children more easily.
The idea is to let the children scroll first, and then when there is no
more space to scroll, the SceneTransitionLayout will use the scroll
events as if they were normal drag events.
The SceneTransitionLayout will continue to intercept scroll events until
 the user lifts their finger or switches to a new scene.

Video before and after this change b/291025415#comment3

Test: mp SystemUIComposeGallery
Bug: 291025415
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:7be51146fe44ed57a3d7e2de501b75ae764a6ff8)
Change-Id: I88940b5dd5d2004f8e0e2870a822bf2c535b0668