* (scripts/prep.sh) prep mpr package at the same time as the arch package
* (contrib/package/makedeb-mpr/) add MPR package
i wanted this on my raspberry pi and i could've done it with docker but
this gives me a systemd service. i haven't actually uploaded this at all
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Signed-off-by: Beethoven <44652883+Beethoven-n@users.noreply.github.com>
