Let sensors also export state interfaces of joints

[christophfroehlich]

• Let sensor export also state interfaces of joints
• Fix returned no state interfaces warning

needed for ros-controls/ros2_control_demos#653

[saikishor]

In general, LGTM

[saikishor]

Thanks for fixing it

[codecov]

Codecov Report

Attention: Patch coverage is 93.22034% with 4 lines in your changes missing coverage. Please review.

Project coverage is 87.77%. Comparing base (3d57fc8) to head (ab0311d).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...dware_interface/test/test_component_interfaces.cpp	93.87%	3 Missing ⚠️
...ce/include/hardware_interface/sensor_interface.hpp	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1885      +/-   ##
==========================================
- Coverage   87.83%   87.77%   -0.06%     
==========================================
  Files         122      122              
  Lines       12926    12978      +52     
  Branches     1153     1156       +3     
==========================================
+ Hits        11353    11391      +38     
- Misses       1148     1159      +11     
- Partials      425      428       +3     

Flag	Coverage Δ
unittests	87.77% <93.22%> (-0.06%)	⬇️

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

Files with missing lines	Coverage Δ
hardware_interface/src/resource_manager.cpp	73.30% <ø> (ø)
...e/test/test_component_interfaces_custom_export.cpp	89.16% <100.00%> (-0.09%)	⬇️
...ce/include/hardware_interface/sensor_interface.hpp	94.00% <87.50%> (-1.35%)	⬇️
...dware_interface/test/test_component_interfaces.cpp	96.36% <93.87%> (-1.28%)	⬇️

... and 1 file with indirect coverage changes

[saikishor]

Looks good in general.

Maybe we don't need these debug prints