m16ib20: update xacro, urdf and meshes based on DH data

As per subject: this commit updates the M-16iB/20 support with a urdf based on the DH data found in the controller. The `tool0` link is also updated, and has the correct position as well as orientation now.

This does not yet include the discussed `base` link which is to coincide with the Fanuc's *World Coordinate* origin. This will be added later.

Updates to the M-16iB/20 MoveIt configuration and plugin packages (in `fanuc_experimental`) will follow.