Feature/dgnss updates

[ksha23]

Overall: Adds RTK GNSS capabilities via ublox package and visualization via mapviz

Details:

• Remove most references to the old GPS/IMU node
• Adds Ublox and Mapviz packages
• Adds new node written in Python that maps Ublox GPS messages to CoordinateMsg
• Created launch files for Ublox/ArduSimple node, mapper node, and mapviz

[Tzanccc]

The submodules have been accidentally deleted in this PR, please revert this change. Also will review the code later.

Comparison between the src folder in this branch and master. Submodules are confirmed missing.