API changes to support robot description

[destogl]

As discussed in #66. This replaces it.

The Admittance Controller changes are in ros-controls/ros2_controllers#

[saikishor]

Minor comments
The rest looks great :)
Thanks for the nice work

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 6 lines in your changes missing coverage. Please review.

Project coverage is 80.20%. Comparing base (41d9e74) to head (0067638).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
...ics_interface_kdl/src/kinematics_interface_kdl.cpp	64.70%	2 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #83      +/-   ##
==========================================
+ Coverage   79.44%   80.20%   +0.75%     
==========================================
  Files           4        4              
  Lines         180      197      +17     
  Branches       18       35      +17     
==========================================
+ Hits          143      158      +15     
- Misses         27       28       +1     
- Partials       10       11       +1     

Flag	Coverage Δ
unittests	80.20% <77.77%> (+0.75%)	⬆️

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

Files with missing lines	Coverage Δ
...lude/kinematics_interface/kinematics_interface.hpp	100.00% <ø> (ø)
...terface_kdl/test/test_kinematics_interface_kdl.cpp	100.00% <100.00%> (ø)
...ics_interface_kdl/src/kinematics_interface_kdl.cpp	67.00% <64.70%> (+0.69%)	⬆️

... and 1 file with indirect coverage changes

[saikishor]

LGTM