Needs an interface that accepts YAML::Node

[b-adkins]

When I tried to use yaml_and_typeinfo_to_rosmsg for a robot application, I found myself having converting a YAML::Node to a string, just so yaml_and_typeinfo_to_rosmsg could re-parse it into a YAML::Node.

In my experience, robot configs that complete even simple tasks require complex YAML trees for their config file. You will be parsing many subtrees into ROS msgs, such as geometry_msgs/Pose and geometry_msgs/TransformStamped.

Specifically, my code would:

1. Parse the tree using yamlcpp.
2. Dive down the YAML tree to the selected key (e.g. yaml_tree["arm"]["waypoints"]["grasp_approach"])
3. Convert that YAML::Node to a string
4. Pass that string to yaml_and_typeinfo_to_rosmsg
5. yaml_and_typeinfo_to_rosmsg re-parses the YAML.

Suggested Change

A new interface:

void yaml_node_and_typeinfo_to_rosmsg(
  const TypeInfo_Cpp * type_info,
  const YAML::Node& yaml_node,
  void * ros_message)

Leave the interface for yaml_and_typeinfo_to_rosmsg the same, but move most of the code inside to yaml_node_and_typeinfo_to_rosmsg.

Likewise for the other functions that take as input a yaml_str.