[Iron] Add new node interface TypeDescriptionsInterface to provide Ge…

…tTypeDescription service (backport ros2#2224) (ros2#2236)

* Add new node interface TypeDescriptionsInterface to provide GetTypeDescription service (ros2#2224)

* TypeDescriptions interface with readonly param configuration

* Add parameter descriptor, to make read only

* example of spinning in thread for get_type_description service

* Add a basic test for the new interface

* Fix tests with new parameter

* Add comments about builtin parameters

* Hide new member for ABI stability

* Add typedescription interface smoke test

Signed-off-by: Emerson Knapp <emerson.b.knapp@gmail.com>
Signed-off-by: William Woodall <william@osrfoundation.org>

rclcpp/include/rclcpp/node.hpp

@@ -57,7 +57,6 @@
 #include "rclcpp/node_interfaces/node_timers_interface.hpp"
 #include "rclcpp/node_interfaces/node_topics_interface.hpp"
 #include "rclcpp/node_interfaces/node_type_descriptions_interface.hpp"
-#include "rclcpp/node_interfaces/node_type_descriptions_interface.hpp"
 #include "rclcpp/node_interfaces/node_waitables_interface.hpp"
 #include "rclcpp/node_options.hpp"
 #include "rclcpp/parameter.hpp"

rclcpp/test/rclcpp/CMakeLists.txt

@@ -179,6 +179,11 @@ ament_add_gtest(test_node_interfaces__node_type_descriptions
 if(TARGET test_node_interfaces__node_type_descriptions)
   target_link_libraries(test_node_interfaces__node_type_descriptions ${PROJECT_NAME} mimick)
 endif()
+ament_add_gtest(test_node_interfaces__node_type_descriptions
+  node_interfaces/test_node_type_descriptions.cpp)
+if(TARGET test_node_interfaces__node_type_descriptions)
+  target_link_libraries(test_node_interfaces__node_type_descriptions ${PROJECT_NAME} mimick)
+endif()
 ament_add_gtest(test_node_interfaces__node_waitables
   node_interfaces/test_node_waitables.cpp)
 if(TARGET test_node_interfaces__node_waitables)