[RenderEngine] Organize RenderEngine directory.

This patch:
1. adds proper namespace renderengine to all RenderEngine code,
   and namespace gl to all GLES related code
2. creates gl/ directory for GLES backend code
3. Reorder include header files, remove unused header files.

BUG: 112585051
Test: Build, flash, run display validation
Change-Id: I81f0b8831213607cde08562958f7c38ddaf4c9e6
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index aab6c22..1a99718 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -215,7 +215,7 @@
         const wp<IBinder>& displayToken,
         const sp<ANativeWindow>& nativeWindow,
         const sp<DisplaySurface>& displaySurface,
-        std::unique_ptr<RE::Surface> renderSurface,
+        std::unique_ptr<renderengine::Surface> renderSurface,
         int displayWidth,
         int displayHeight,
         bool hasWideColorGamut,