[fix][feat] Fix and update GPS use

Main changes :

• Allow to estimate the calibration between SLAM base and GPS using a trajectory portion (offset not necessary)
• Compute and broadcast the offset at each PGO
• Remove not usable functions (in the sens of SLAM process)
• Fix bad frame id for GPS

WARNING : if odom frame and GPS ref frame are 180° oriented and the GPS covariance is too low or the GPS frequency is too low, the first PGO optimization might fail (gps/base poses might be too far from each others). Maybe the odom frame can be rotated roughly in this case.