libyang MAINTENANCE cleanup header includes

Use iwyu tool and fix which headers are included
diff --git a/src/tree_schema_helpers.c b/src/tree_schema_helpers.c
index 2ed6344..9417d13 100644
--- a/src/tree_schema_helpers.c
+++ b/src/tree_schema_helpers.c
@@ -25,6 +25,7 @@
 #include "common.h"
 #include "compat.h"
 #include "context.h"
+#include "dict.h"
 #include "hash_table.h"
 #include "in.h"
 #include "in_internal.h"
@@ -34,7 +35,6 @@
 #include "schema_features.h"
 #include "set.h"
 #include "tree.h"
-#include "tree_data.h"
 #include "tree_edit.h"
 #include "tree_schema.h"
 #include "tree_schema_internal.h"