Add pre-threshold fling vibration for Back gesture

Bug: 290869686
Test: Manual
(cherry picked from commit 2354d4d1)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:151f3a646abbffd271b0787ed8fb9413849ea1e7)
Merged-In: Iad0991724c75c0a63d8a14c313a143a9be660137
Change-Id: Iad0991724c75c0a63d8a14c313a143a9be660137