[Spawner] Allow arguments per controller instead of global args

[saikishor]

This PR adds some changes to the Spawner to allow it to define the controller args per controller rather than global args for all the controllers.

I've added a new function in the launch_utils and I tested it using the following changes in example_12
https://github.com/ros-controls/ros2_control_demos/blob/advanced_spawner/example_12/bringup/launch/rrbot.launch.py

With this change we can do both the following

ros2 run controller_manager spawner ctrl_1 ctrl_2 --inactive --controller-ros-args ....

and

ros2 run controller_manager spawner --controller ctrl_1 --load-only --controller ctrl_2 --inactive --controller-ros-args ...

[codecov]

Codecov Report

❌ Patch coverage is 81.97115% with 75 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.27%. Comparing base (44cbd9c) to head (227e4a4).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...troller_manager/controller_manager/launch_utils.py	2.56%	38 Missing ⚠️
controller_manager/controller_manager/spawner.py	78.50%	15 Missing and 8 partials ⚠️
controller_manager/test/test_advanced_spawner.cpp	94.81%	0 Missing and 14 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2895      +/-   ##
==========================================
- Coverage   89.40%   89.27%   -0.14%     
==========================================
  Files         157      158       +1     
  Lines       18781    19155     +374     
  Branches     1510     1549      +39     
==========================================
+ Hits        16791    17100     +309     
- Misses       1369     1417      +48     
- Partials      621      638      +17     

Flag	Coverage Δ
unittests	89.27% <81.97%> (-0.14%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
controller_manager/test/test_advanced_spawner.cpp	94.81% <94.81%> (ø)
controller_manager/controller_manager/spawner.py	72.64% <78.50%> (+2.23%)	⬆️
...troller_manager/controller_manager/launch_utils.py	22.97% <2.56%> (-22.75%)	⬇️

... and 1 file with indirect coverage changes

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[mergify]

This pull request is in conflict. Could you fix it @saikishor?

[christophfroehlich]

I think this is a great idea.

I tested this successfully with ros-controls/ros2_control_demos#1030 and have some notes with possible improvements:

• How can we add a hint to the --controller argument from ros2 run controller_manager spawner --help?
• does it make sense/would it be possible to give more than one controller with one --controller option "block", see the two pid controllers in the linked example which have identical settings.

[bmagyar]

@saikishor @christophfroehlich I've implemented the --controller hint using a dummy arg. The other version was to use an epilogue thing from argparse which would look weird in the user output. Tests keep things working even though the current thing is a liiiiiiiiiiittle hacky but it works nicely. I think we should merge the PR as-is

[saikishor]

@saikishor @christophfroehlich I've implemented the --controller hint using a dummy arg. The other version was to use an epilogue thing from argparse which would look weird in the user output. Tests keep things working even though the current thing is a liiiiiiiiiiittle hacky but it works nicely. I think we should merge the PR as-is

LGTM. Thanks