Add Debian, Ubuntu and Mint candidate profiles with scoped systemd 255 credentials

source/packaging/framebridge-credential-helper

@@ -0,0 +1,3 @@
+#!/bin/sh
+# Installed root-owned; never run a privileged helper from an owner checkout.
+exec /usr/bin/python3 -I -S /usr/lib/framebridge-expanded/expanded/framebridge_expanded/credential_helper.py "$@"