ART: Clean up thread.h and thread_list.h

Remove dependency on stack.h and gc_root.h. Remove unused object
callbacks include. Factor out ManagedStack into its own set of files.
Fix up users of transitive includes.

Test: m test-art-host
Change-Id: I01286c43d8c7710948c161b1348faabb05922e59
diff --git a/runtime/openjdkjvmti/ti_heap.cc b/runtime/openjdkjvmti/ti_heap.cc
index 99774c6..319b1c2 100644
--- a/runtime/openjdkjvmti/ti_heap.cc
+++ b/runtime/openjdkjvmti/ti_heap.cc
@@ -35,6 +35,7 @@
 #include "primitive.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"
+#include "stack.h"
 #include "thread-inl.h"
 #include "thread_list.h"