bullet-featherstone - add applied constraint force torque to joint transmitted wrench

[iche033]

🦟 Bug fix

Summary

Updated JointTransmittedWrench function to account for forces and torques applied by constraints, e.g. when velocity commands are sent, bullet uses a motor constraint to move the joint. The force torque feedback in this case is now consistent with what dartsim produces.

Test was originally written by @scpeters and Nils Berg so credit goes to them.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[scpeters]

just two small changes to the test and I'll be ready to approve

thanks for your patience on my review