[JTC] Enable feed-forward effort trajectories

[VladimirIvan]

• Adds support for using the effort field in the trajectory message for JTCs that claim the effort command interface (warning message is no longer displayed).
• For effort only controllers, the desired effort is added to the PID effort as a feed forward term.
• Adds support for claiming a combination of position, effort command interfaces. The desired effort will be passed directly to the effort interface in this case (no PID is calculated). Positions are passed to directly to the position interface. This is useful when the harware runs a PID with a feed-forward term at a higher rate on the motor driver.
• Adds tests for above features and changes testing logic.
• Tested on hardware.
• Passed local tests and pre-commit.
• Updated docs.