Add controller dependency graph for ::AUTO switch mode

[saikishor]

This PR aims to add the things needed for the ::AUTO switch mode and addresses few other things.

With the ::AUTO switch mode, you can activate and deactivate the whole chain

graph LR;
    A-->B;
    B-->C;
    C-->D;
    D-->E;

Loading

Here, you can activate the whole chain, activating controller A alone and deactivate the whole chain deactivating the controller E

graph LR;
    A-->B;
    B-->C;
    B-->D;
    D-->E;

Loading

Here, you can activate the whole chain, activating controller A alone and deactivate the whole chain deactivating the controller E and C

Activating controller D will only activate D and E
Activating controller B will activate B, C, D and E

[codecov]

Codecov Report

❌ Patch coverage is 91.12150% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.35%. Comparing base (56fc052) to head (cb75751).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ger/include/controller_manager/controller_spec.hpp	86.86%	13 Missing and 13 partials ⚠️
controller_manager/src/controller_manager.cpp	86.20%	7 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2578      +/-   ##
==========================================
+ Coverage   89.31%   89.35%   +0.04%     
==========================================
  Files         145      145              
  Lines       16541    16931     +390     
  Branches     1396     1426      +30     
==========================================
+ Hits        14773    15129     +356     
- Misses       1231     1249      +18     
- Partials      537      553      +16     

Flag	Coverage Δ
unittests	89.35% <91.12%> (+0.04%)	⬆️

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Files with missing lines	Coverage Δ
...controller_interface/controller_interface_base.hpp	91.66% <ø> (ø)
.../include/controller_manager/controller_manager.hpp	96.87% <ø> (ø)
...ontroller_manager/test/test_controller_manager.cpp	95.92% <100.00%> (+0.38%)	⬆️
...ller_manager/test/test_controller_manager_srvs.cpp	99.36% <100.00%> (+0.02%)	⬆️
...e_interface/include/hardware_interface/helpers.hpp	100.00% <100.00%> (+3.44%)	⬆️
hardware_interface/test/test_helpers.cpp	93.33% <100.00%> (+7.61%)	⬆️
controller_manager/src/controller_manager.cpp	75.33% <86.20%> (+0.16%)	⬆️
...ger/include/controller_manager/controller_spec.hpp	87.19% <86.86%> (-12.81%)	⬇️

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