Add supercap communication driver

[calebchalmers]

Blocked: requires the hardware side of supercaps to be testable.

Details are TBD, but this will likely be an I2C-based driver with the following messages:

Firmware -> Device

• Current chassis power draw (inferred from motor current)
• Maximum allowed power draw (from ref system)

Device -> Firmware

• Current energy stored
• Max energy capacity

To start, a basic driver which handles these messages and tracks the variables would be ideal. Once complete, we can make new issues to begin integrating the supercaps into the chassis subsystem.