split sound_play_msgs package

[knorth55]

split sound_play_msgs package from sound_play

[rkent]

I have tested this PR its original form with smoke tests of audio_capture, audio_play, and sound_play under humble, jazzy, kilted, and rolling (I have a Docker environment for audio ROS development that makes this easy to do.) Everything worked when compiling the full repository.

However, there are a number of minor issues in the configuration files noted below that should be updated. One example that will fail without these changes is:

colcon build --packages-up-to sound_play

on a fresh workspace. Some of these changes may not be technically necessary, but are intended to follow the examples in ROS 2 documentation.

Overall though this works.

[rkent]

Here's another issue to resolve. You need to add to sound_play/package.xml:

   <exec_depend>ament_index_python</exec_depend>
   <exec_depend>action_msgs</exec_depend>

These are used in libsoundplay.py. Without them, the python documentation generated by rosdoc2 fails.

[knorth55]

@rkent
Thank you for your review and sorry for update.
I update this PR and follow your feedback!

Could you check this PR again if possible?