Connect GPS to robot_localization

[erickmu1]

Description:

• GPS is connected differently to the robot_localization package than any other odometry sensor
• Connect GPS using the navsat node (part of robot_localization)

Goals:

• [x] Connect GPS to the robot_localization package

Acceptance Criteria:

• [ ] Robot navigates by leveraging GPS appropriately

Notes:

• There seems to be known problems between trying to use GPS and loop closure detection in RTAB map. One must also investigate what the issues are and how to work around them

[erickmu1]

Good reference on how to add GPS and why we need an IMU with a compass: https://answers.ros.org/question/202117/integrate-a-gps-sensor-with-robot_localization-and-use-move_base-node/

[erickmu1]

To get a general idea of why we want to do this: https://commons.trincoll.edu/trinityrobotics/basic-odometry-and-localization/

[erickmu1]

Here is an example config file for using robot_localization ekf_localization_nodes for both local odometry and fusing navsat_transform_node output to get absolute odometry info: https://github.com/cra-ros-pkg/robot_localization/blob/melodic-devel/params/dual_ekf_navsat_example.yaml#L86