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/optimizing/nodes.h b/compiler/optimizing/nodes.h
index d13f5b4..d4382c6 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -30,8 +30,8 @@
 #include "base/transform_array_ref.h"
 #include "data_type.h"
 #include "deoptimization_kind.h"
-#include "dex_file.h"
-#include "dex_file_types.h"
+#include "dex/dex_file.h"
+#include "dex/dex_file_types.h"
 #include "entrypoints/quick/quick_entrypoints_enum.h"
 #include "handle.h"
 #include "handle_scope.h"