Unable to send single character

[Karsten1987]

When trying to send a single character between two python nodes, the system crashes with:

Unexpected condition: string capacity was zero for allocated data! Exiting.

The error comes from a c-string not being properly allocated: https://github.com/ros2/rosidl/blob/master/rosidl_runtime_c/src/string_functions.c#L46-L51

To reproduce:
Terminal 1:

RMW_IMPLEMENTATION=rmw_iceoryx_cpp ros2 topic pub /chatter std_msgs/msg/String "{data: 1}"

Terminal 2:

RMW_IMPLEMENTATION=rmw_iceoryx_cpp ros2 topic echo /chatter std_msgs/msg/String

As far as I can tell, this issue is not having with a c++ typesupport.

[Karsten1987]

fixed with #30