Introduce Modifier.nestedScrollController()

This CL introduces Modifier.nestedScrollController(), which can be used
to disable an outer scrollable when a nested scrollable has reached its
bounds after consuming some scroll deltas.

See b/383288923 and ag/30578539 for more discussions about this.

Bug: 383288923
Test: atest NestedScrollControllerTest
Flag: EXEMPT this is not used anywhere yet
Change-Id: I905e5dd4b14ed95c40b26bed3ec444c17937e6a1