Create dex subdirectory

Move all the DexFile related source to a common subdirectory dex/ of
runtime.

Bug: 71361973
Test: make -j 50 test-art-host
Change-Id: I59e984ed660b93e0776556308be3d653722f5223
diff --git a/compiler/compiler.cc b/compiler/compiler.cc
index 47f44ff..60977b6 100644
--- a/compiler/compiler.cc
+++ b/compiler/compiler.cc
@@ -19,7 +19,7 @@
 #include <android-base/logging.h>
 
 #include "base/macros.h"
-#include "code_item_accessors-inl.h"
+#include "dex/code_item_accessors-inl.h"
 #include "driver/compiler_driver.h"
 #include "optimizing/optimizing_compiler.h"
 #include "utils.h"