[Pod] Implement temperature measurements from thermistor via ADC

[taesungh]

To measure the temperature of the linear induction motor, we'll be using thermistors measured with an ADS1015 ADC which communicate by I2C.

• Create an abstraction for the LIM temperature
  • We might eventually have a higher-level abstraction for the entire linear induction motor component
  • Since we have multiple thermistors, this abstraction might need to manage multiple ADC instances
• Provide a method to get the temperature readings as a tuple or struct for each of the thermistor regions
  • We can assume a linear scaling factor for now although the actual temperature curve may be more complex

Similar to #34, we should be able to use eldruin/ads1x1x-rs together with the I2c instance from RPPAL.

[taesungh]

Reopening as still need temperature conversion.