🚀 Add PID controller 🎉

[destogl]

Proposal for a new controller that provides PID functionality.

The controller can be used stand-alone, in a chain.
Measured states can be provided through the topic or state interface, depening on the concrete control arch.
For example, if you are having an external estimator, using topic might be eaiser at first then full integration into ros2_control.

The PR depends the following changes:

• Propose generic messages for commanding and getting states from controllers. control_msgs#69
• [PidROS] Enable interpreting prefix as param prefix. control_toolbox#129

Looking forward for your feedback!

Testing dependencies:

  control_msgs:
    type: git
    url: git@github.com:ros-controls/control_msgs.git
    version: add-generic-msgs-for-controller-references
  control_toolbox:
    type: git
    url: git@github.com:ros-controls/control_toolbox.git
    version: add-option-to-define-prefix-as-param-prefix
  ros2_controllers:
    type: git
    url: git@github.com:StoglRobotics-forks/ros2_controllers.git
    version: add-pid-controller

[codecov-commenter]

Codecov Report

Merging #434 (d0cb6e2) into master (23f944f) will increase coverage by 0.60%.
The diff coverage is n/a.

❗ Current head d0cb6e2 differs from pull request most recent head 40b9360. Consider uploading reports for the commit 40b9360 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #434      +/-   ##
==========================================
+ Coverage   46.73%   47.33%   +0.60%     
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  Files          40       40              
  Lines        3640     3640              
  Branches     1718     1718              
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+ Hits         1701     1723      +22     
+ Misses        749      725      -24     
- Partials     1190     1192       +2     

Flag	Coverage Δ
unittests	47.33% <ø> (+0.60%)	⬆️

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see 2 files with indirect coverage changes

[mergify]

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

[christophfroehlich]

Can we backport this to iron and humble?