[Transmissions] Add force interface

[jordan-palacios]

Follow up on #2310.

Same concept and approach, only this time we add force and current interfaces.

As before, adding these two new interfaces is backwards compatible. If force and current interfaces are not available then the contents from this PR do nothing.

[codecov]

Codecov Report

❌ Patch coverage is 86.15385% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.38%. Comparing base (c993e5b) to head (c692024).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
...ansmission_interface/differential_transmission.hpp	76.19%	3 Missing and 2 partials ⚠️
...ude/transmission_interface/simple_transmission.hpp	55.55%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2588      +/-   ##
==========================================
- Coverage   89.40%   89.38%   -0.03%     
==========================================
  Files         151      151              
  Lines       17024    17085      +61     
  Branches     1420     1424       +4     
==========================================
+ Hits        15220    15271      +51     
- Misses       1250     1255       +5     
- Partials      554      559       +5     

Flag	Coverage Δ
unittests	89.38% <86.15%> (-0.03%)	⬇️

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

Files with missing lines	Coverage Δ
..._interface/test/differential_transmission_test.cpp	99.57% <100.00%> (+0.05%)	⬆️
...ission_interface/test/simple_transmission_test.cpp	100.00% <100.00%> (ø)
...ude/transmission_interface/simple_transmission.hpp	76.38% <55.55%> (-0.89%)	⬇️
...ansmission_interface/differential_transmission.hpp	79.75% <76.19%> (-0.81%)	⬇️

... and 1 file with indirect coverage changes

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[saikishor]

After some discussion, we are not sure if the current makes sense at the joint end. It is better to be only on the actuator end the conversion from Nm/N to Amp.

[jordan-palacios]

After some discussion, we are not sure if the current makes sense at the joint end. It is better to be only on the actuator end the conversion from Nm/N to Amp.

Yeah, I have to agree. I was kinda realizing the same thing when I was coding the differential transmission part. Current does not really make sense at joint level. Will fix.

@christophfroehlich Thanks for spotting the typo ( 😭 ). In the end I'll remove all the "curret" related stuff.

[saikishor]

LGTM. It is missing the release_notes

[mergify]

This pull request is in conflict. Could you fix it @jordan-palacios?

[christophfroehlich]

Let's merge it as it is, and rethink the check possibly in a separate PR.