Constify the exported state interfaces using ConstSharedPtr

[saikishor]

As discussed in #1688, this PR aims to export the ConstSharedPtr of the StateInterfaces from thew hardware components and internally within the ResourceManager

[codecov]

Codecov Report

Attention: Patch coverage is 93.93939% with 2 lines in your changes missing coverage. Please review.

Project coverage is 86.90%. Comparing base (1c7a5d1) to head (2205989).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ce/include/hardware_interface/system_interface.hpp	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1767      +/-   ##
==========================================
- Coverage   86.92%   86.90%   -0.03%     
==========================================
  Files         118      118              
  Lines       11436    11438       +2     
  Branches     1051     1051              
==========================================
- Hits         9941     9940       -1     
- Misses       1129     1131       +2     
- Partials      366      367       +1     

Flag	Coverage Δ
unittests	86.90% <93.93%> (-0.03%)	⬇️

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

Files with missing lines	Coverage Δ
...oller_interface/chainable_controller_interface.hpp	100.00% <ø> (ø)
...lude/controller_interface/controller_interface.hpp	100.00% <ø> (ø)
...controller_interface/controller_interface_base.hpp	90.00% <ø> (ø)
...r_interface/src/chainable_controller_interface.cpp	54.71% <100.00%> (+0.43%)	⬆️
controller_interface/src/controller_interface.cpp	75.00% <ø> (ø)
...rface/test/test_chainable_controller_interface.cpp	100.00% <100.00%> (ø)
controller_manager/src/controller_manager.cpp	76.83% <100.00%> (-0.25%)	⬇️
..._interface/include/hardware_interface/actuator.hpp	100.00% <ø> (ø)
.../include/hardware_interface/actuator_interface.hpp	94.11% <100.00%> (ø)
...re_interface/include/hardware_interface/handle.hpp	100.00% <ø> (ø)
... and 9 more

[christophfroehlich]

LGTM

[mergify]

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

[destogl]

Great! Thanks!