Implement CAN interface on MSB

[bjackson312006]

Description

This repo currently has a u_can.c and u_can.h, but there's nothing in them. These files should be implemented to offer the same CAN functionality as the other repos.

Proposed Solution

• Implement u_can.c and u_can.h. Because MSB uses the same STM32 as VCU, the u_can.c and u_can.h can probably be copied over from Cerberus-2.0 for the most part.
• It's probably also a good idea to double-check that the CAN configuration in the CubeMX project matches what's on Altium here.
• The FDCAN callback function also has to be implemented (HAL_FDCAN_RxFifo0Callback). See main.c in Cerberus-2.0 for an example