[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/RenderEngine/Image.cpp b/services/surfaceflinger/RenderEngine/Image.cpp
index ee140eb..cabcace 100644
--- a/services/surfaceflinger/RenderEngine/Image.cpp
+++ b/services/surfaceflinger/RenderEngine/Image.cpp
@@ -19,12 +19,11 @@
 #include <vector>
 
 #include <log/log.h>
-
-#include <renderengine/GLExtensions.h>
 #include <renderengine/RenderEngine.h>
+#include "gl/GLExtensions.h"
 
 namespace android {
-namespace RE {
+namespace renderengine {
 
 Image::~Image() = default;
 
@@ -43,7 +42,7 @@
     attrs.push_back(EGL_IMAGE_PRESERVED_KHR);
     attrs.push_back(EGL_TRUE);
 
-    if (isProtected && GLExtensions::getInstance().hasProtectedContent()) {
+    if (isProtected && gl::GLExtensions::getInstance().hasProtectedContent()) {
         attrs.push_back(EGL_PROTECTED_CONTENT_EXT);
         attrs.push_back(EGL_TRUE);
     }
@@ -74,6 +73,6 @@
     return true;
 }
 
-} // namespace impl
-} // namespace RE
-} // namespace android
+}  // namespace impl
+}  // namespace renderengine
+}  // namespace android