[choreolib] [cpp] Trajectory::GetTotalTime() doesn't unwrap optional, renders class virtually unusable

[bathtubed]

In Trajectory.h

  /**
   * The total time the trajectory will take to follow
   *
   * @return The total time the trajectory will take to follow, if empty will
   * return 0 seconds.
   */
  units::second_t GetTotalTime() const {
    if (samples.size() == 0) {
      return 0_s;
    }
    return GetFinalSample().GetTimestamp();
  }

Code which uses GetTotalTime (or SampleAt, which calls into GetTotalTime) breaks due to the return statement in this method. GetFinalSample returns an optional so it should read

return GetFinalSample().value().GetTimestamp();

The optional doesn't need to be checked since the method already verifies that the trajectory isn't empty.

I would submit a PR but I don't have the bandwidth right now to set up an entire testing environment just to add 8 characters to a file, so I apologize.