Create software skeleton classes for sensors

[kevinl120]

Create skeleton classes for the following sensors:

• ADS1115 (ADC) (Implement software polling for ADC (ADS1115) #25)
• DPS422XTSA1 (Altimeter) (Implement software polling for Altimeter (DPS422XTSA1) #26)
• MTK3339 (GPS) (Implement software polling for GPS (MTK3339) #27)

Requirements:

• Sensor source files should be created in ./Software/spartan/src/sensors/
• Each class must inherit from the sensor base class.
• Each class must implement virtual functions of the sensor base class. (Since this issue is only to create the skeleton, the body of each function can be empty). More details here.
• Source files should be added to CMake configuration files and the project should build error-free.