SF: Track last client composition's acquire fence

Currently CompositionEngine uses the acquire fence from the current
client composition as part of the release fence of the last buffer. This
is rather suboptimal, as technically if the last buffer was client
composited it should use the target acquire fence from the last client
composition instead.

This CL adds two new methods to LayerFE to set and get last client
composition acquire fence to use as the release fence.

Flag: com.android.graphics.surfaceflinger.flags.force_slower_follower_gpu_composition
Bug: 435237397
Test: New test cases in libcompositionengine_test
Change-Id: I40bb8f19f1c7a75b81c2ac449fe82f6b602597fd