rmw_fastrtps_dynamic_cpp shouldn't require rosidl_typesupport_fastrtps_*

[ivanpauno]

Feature request

Feature description

Currently, it's impossible to make a single rmw single typesupport build for rmw_fastrtps_dynamic_cpp, as it currently depends on rosidl_typesupport_fastrtps_c/cpp:

rmw_fastrtps/rmw_fastrtps_dynamic_cpp/package.xml

Lines 27 to 28 in 98d1472

	<build_depend>rosidl_typesupport_introspection_c</build_depend>
	<build_depend>rosidl_typesupport_introspection_cpp</build_depend>

That dependency was introduced to use some utility functions available there.
It could be removed if the utility functions are moved to a common package.

[MiguelCompany]

That dependency was introduced to use some utility functions available there.
It could be removed if the utility functions are moved to a common package

The dependency is there just for the u16string <-> wstring conversions. Perhaps rosidl_runtime_c and/or rosidl_runtime_cpp are good candidates for those functions?

[ivanpauno]

Sounds good to me

[ZhenshengLee]

Can be closed?

[MiguelCompany]

I don't think so, since rmw_fastrtps_dynamic_cpp still requires rosidl_typesupport_fastrtps_* here