libyang MAINTENANCE cleanup header includes

Use iwyu tool and fix which headers are included
diff --git a/src/tree_data_free.c b/src/tree_data_free.c
index ffeb9d5..cf70bf7 100644
--- a/src/tree_data_free.c
+++ b/src/tree_data_free.c
@@ -16,6 +16,7 @@
 #include <stdlib.h>
 
 #include "common.h"
+#include "dict.h"
 #include "hash_table.h"
 #include "log.h"
 #include "plugins_types.h"