idl: remove for_each from fragmented serialization

Previously fragmented buffers of bytes were serialized
with a for_each loop. Since serializing bytes involves writing
size first and then data, only first fragment (and its size)
would be taken into account.
This commit changes fragmented code generation so it expects
that serialized range has a serialize(output, T) specification
and expects it to iterate over fragments on its own (just like
serializer for basic_value_view does).

Fixes #3501

idl-compiler.py

@@ -439,10 +439,7 @@ def add_param_writer_basic_type(name, base_state, typ, var_type = "", var_index
         GCC6_CONCEPT(requires FragmentRange<FragmentedBuffer>)
         after_${base_state}__$name<Output> write_fragmented_$name$var_type(FragmentedBuffer&& fragments) && {
             $set_varient_index
-            using boost::range::for_each;
-            for_each(fragments, [&] ($typ t) {
-                serialize(_out, t);
-            });
+            serialize_fragmented(_out, std::forward<FragmentedBuffer>(fragments));
             $set_command
             return $return_command;
         }""")).substitute(locals())