Add xtasks #58
Description
Consider adding a justfile
just build - build Pico and Nucleo as release binaries with info logging
just flash-pico - flash a Neotron Pico BMC
just flash-nucleo - flash an ST Nucleo
just fmt - all four crates
just clippy - ditto
just check - ditto
This works around the fact we don't have everything in one workspace.