Adds a flush jank data layer state update type.

A transaction can be sent to SurfaceFlinger with a layer state change
of this type to wake up SurfaceFlinger and have it perform the layer
state update logic, without updating anything, but triggering any
side-effects, especially jank data processing.

Bug: 235178314
Bug: 221393601
Bug: 225105422
Test: atest SurfaceFlinger_test
Change-Id: Idf458c96cbe8f54224ebde6f517c08b9a5c48a06