Layered LEDs

• Refactors the CANdle sensor to use "layers", where each layer holds a separate set of segments with separate configs, and higher index layers have higher priority.
  • When a higher priority layer has a segment with a set color or animation, that layer is shown above all others below it, even if some segments are black.
  • If a layer does not have a set color or animation, it is considered empty and does not get shown - a lower priority layer is allowed to show through.
• The PIT sequence now uses this to display a progress bar that gets ticked with each step - resolves #105
• Added the ability to set individual LEDs, but these get overridden whenever the segment that the LED belongs to is written to
• Drivetrain uses this to display the magnet health of azimuth CANcoders on the first 4 LEDs of the CANdle - resolves #107