NAV-ISS-21 Fix/Clean up Sensor Proto

[briellelaw]

Looks like we are using incorrect data types for some of the fields.
Ie. gps ground_speed, track_made_good, mag_var should all be float

There is also a bunch of fields that I don't think we are using anymore.
Ie. gps magnetic_var_sense and gps_latitude_loc etc.

[briellelaw]

Note - after updating Sensor proto, remember to update dependent files as well.
This includes:

• uri.h
• uri.py
• Help.h
• Help.py