Resolve btr dependency in cram_robot_pose_gaussian

[cpollok]

The package cram_robot_pose_gaussian depends on cram_bullet_reasoning and cram_bullet_reasoning_belief_state. Since cram_3d_world builds on top of cram_common and cyclical dependcies are bad, it would be good to get rid of this dependency.
Also the dependency is not listed in the asdf but the function visible-location-validator in current-pose-generator-and-pose-validator.lisp uses functions from btr and btr-belief.

It would be best if we could remove the dependency somehow.