Persist input gestures on IoThread in background

Previously, gestures were being persisted on the DisplayThread
foreground thread handler. This updates gestures to be persisted
on the background IoThread.

Bug: b/383380006
Bug: b/383380875
Test: Verified on device that functionality still works
Flag: EXEMPT bugfix

Change-Id: I103d2e03151c84152beebe4d2a81b2e813e3ee6c