Add example that runs on a microcontroller

[samcrow]

Follow-up from https://github.com/samcrow/canadensis/issues/33

Choose hardware

The hardware should be reasonably low-cost and common. The ideal board would have a microcontroller with CAN FD built in, and a CAN FD transceiver on the board. If that doesn't exist, we could use a CAN FD transceiver expansion board that plugs in to the base board. A separate transceiver board with discrete wires would be too slow and error-prone to set up every time I need to run a test.

Hardware ideas:

Brand	Part number	Price	Microcontroller	CAN	Other features	Existing Rust support
NXP	MR-CANHUBK344	$188	NXP S32K344	6x CAN FD	100BASE-T1 Ethernet	Nothing, but at least it's Cortex-M and has an SVD file
NXP	UCANS32K1SIC	$16	NXP S32K146	2x CAN FD		Nothing, but at least it's Cortex-M and has an SVD file
ST	STM32G0C1E-EV	$296	STM32G0C1	2x CAN (not FD)		HAL
LXRobotics	CyphalPicoBase/CAN	€40	RP2040 with MCP2515 CAN controller	1x CAN (not FD)		HAL
RaccoonLab	uNODE	€70	STM32F103	1x CAN (not FD)		HAL
LXRobotics	Pika Spark	€840	NXP® i.MX 8M Mini (Linux)	2x CAN FD	10BASE-T1S Ethernet	Good (it's Linux)

Make an application

To start, this probably just needs to have heartbeats, node information, and space to add more functionality.