[MockHardware] Added dynamic simulation functionality.

[destogl]

@fmauch please check :)

2. part of port from [GenericSystem] Add velocity-only mode in fake_components  #540

@livanov93 I didn't do parallel use of position and velocity interfaces. I wasn't sure how this should be done. Feel free to extend as needed!

[codecov-commenter]

Codecov Report

Merging #1028 (16d971b) into master (925f5f3) will decrease coverage by 2.44%.
Report is 524 commits behind head on master.
The diff coverage is 35.38%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1028      +/-   ##
==========================================
- Coverage   34.61%   32.18%   -2.44%     
==========================================
  Files          52       94      +42     
  Lines        2981    10175    +7194     
  Branches     1855     6882    +5027     
==========================================
+ Hits         1032     3275    +2243     
- Misses        310      785     +475     
- Partials     1639     6115    +4476     

Flag	Coverage Δ
unittests	32.18% <35.38%> (-2.44%)	⬇️

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

Files	Coverage Δ
...oller_interface/chainable_controller_interface.hpp	100.00% <100.00%> (ø)
...lude/controller_interface/controller_interface.hpp	100.00% <100.00%> (ø)
controller_interface/src/controller_interface.cpp	100.00% <100.00%> (+66.66%)	⬆️
controller_manager/src/controller_manager.cpp	37.94% <ø> (-1.77%)	⬇️
...chainable_controller/test_chainable_controller.hpp	100.00% <100.00%> (ø)
...r_manager/test/test_controller/test_controller.hpp	100.00% <100.00%> (ø)
..._interface/include/hardware_interface/actuator.hpp	100.00% <ø> (ø)
...de/hardware_interface/loaned_command_interface.hpp	100.00% <100.00%> (+14.28%)	⬆️
...re_interface/include/hardware_interface/sensor.hpp	100.00% <ø> (ø)
...re_interface/include/hardware_interface/system.hpp	100.00% <ø> (ø)
... and 70 more

... and 20 files with indirect coverage changes

[mergify]

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

[christophfroehlich]

looking forward to it (and to a new demo example besides ros-controls/ros2_control_demos#254 with velocity interface ;) )

[fmauch]

Apart from my comment about user feedback this looks good an I tested it with a mocked UR5.

[christophfroehlich]

I tested this one successfully with the diffbot from the demos: ros-controls/ros2_control_demos#357