SF: Introduce LayerSnapshot and LayerSnapshotBuilder

Create a builder that walks through the layer hierarchy
to build an ordered list of LayerSnapshots that can be
passed on to CompositionEngine.

This builder does a minimum amount of work to update
an existing set of snapshots based on hierarchy changes
and RequestedLayerState changes.

The builder also introduces a fast path to update
snapshots when there are only buffer updates.

Additionally, pull out LayerSnapshot class from LayerFE
and move it to frontend package.

Bug: 238781169
Test: presubmit
Change-Id: I3fbd6d60968950df2ee97d975c72f9e0aa31b007
diff --git a/services/surfaceflinger/FrontEnd/LayerLifecycleManager.cpp b/services/surfaceflinger/FrontEnd/LayerLifecycleManager.cpp
index fdf60b3..5514c06 100644
--- a/services/surfaceflinger/FrontEnd/LayerLifecycleManager.cpp
+++ b/services/surfaceflinger/FrontEnd/LayerLifecycleManager.cpp
@@ -210,10 +210,7 @@
                 layer->touchCropId = linkLayer(layer->touchCropId, layer->id);
             }
 
-            mGlobalChanges |= layer->changes &
-                    (RequestedLayerState::Changes::Hierarchy |
-                     RequestedLayerState::Changes::Geometry |
-                     RequestedLayerState::Changes::Content);
+            mGlobalChanges |= layer->changes;
         }
     }
 }