[SurfaceFlinger] Add hwc information to winscope:

* String blob of HWC dump
* Fill in HWC composition enum

Caveat is that only the primary display information is filled in.

Bug: 119443475
Test: Winscope trace
Change-Id: I246dc8df5e16388d8e58afeabfe944b158e1a39d
diff --git a/services/surfaceflinger/layerproto/layerstrace.proto b/services/surfaceflinger/layerproto/layerstrace.proto
index bee17d2..ac33a0e 100644
--- a/services/surfaceflinger/layerproto/layerstrace.proto
+++ b/services/surfaceflinger/layerproto/layerstrace.proto
@@ -48,4 +48,7 @@
     optional string where = 2;
 
     optional LayersProto layers = 3;
+
+    // Blob for the current HWC information for all layers, reported by dumpsys.
+    optional string hwc_blob = 4;
 }