Promote unmeasured cov to ProcessorMotion

Some variables related to the noise levels not measured by the motion measurements rendered the motion covariance singular.

The fixes were spread across multiple derivations of ProcessorMotion.

This MR has moved to the base class ProcessorMotion these variables.

include/base/processor/processor_diff_drive.h

@@ -29,7 +29,6 @@ struct ProcessorParamsDiffDrive : public ProcessorParamsMotion
 //  {
 //      time_tolerance = _time_tolerance;
 //  }
-  Scalar unmeasured_perturbation_std = 0.0001;
 };
 
 /**
@@ -62,7 +61,6 @@ protected:
 
   /// @brief Intrinsic params
   ProcessorParamsDiffDrivePtr params_motion_diff_drive_;
-  MatrixXs unmeasured_perturbation_cov_;
 
   virtual void computeCurrentDelta(const Eigen::VectorXs& _data,
                                    const Eigen::MatrixXs& _data_cov,