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/dexoptanalyzer/dexoptanalyzer.cc b/dexoptanalyzer/dexoptanalyzer.cc
index eead2dc..bedc457 100644
--- a/dexoptanalyzer/dexoptanalyzer.cc
+++ b/dexoptanalyzer/dexoptanalyzer.cc
@@ -23,7 +23,7 @@
 #include "base/logging.h"  // For InitLogging.
 #include "compiler_filter.h"
 #include "class_loader_context.h"
-#include "dex_file.h"
+#include "dex/dex_file.h"
 #include "noop_compiler_callbacks.h"
 #include "oat_file_assistant.h"
 #include "os.h"