Add aliases for duplicate poses

[alexander-sung]

Duplicate poses, i.e. different symbols representing the same pose, in the pick_n_place demo are handled by

• still not supporting them directly, thus the warning remains,
• introducing pose aliases in the config file and on the rosparam server,
• reading the pose aliases in the pick_n_place demo to get the actual pose name.

Note that this replaces "pick_pose" and "place_pose" in the output by their concrete table pose symbol.

Requires: https://git.ni.dfki.de/mobipick/mobipick/-/merge_requests/21