Comment 15 for bug 1883122

As part of an effort to surface more detailed/machine-readable content that snappy and subiquity can rely on, we are now looking to add `cloud-init status --format=json` or yaml output which now surfaces a boot_status_code key which can be one of the following:

     - 'unknown': systemd generators and ds-identify haven't run yet to
                  determine if cloud-init should be run during this boot
     - 'disabled-by-marker-file': /etc/cloud/cloud-init.disabled exists
                  which prevents cloud-init from ever running
     - 'disabled-by-generator': systemd generator ran ds-identify and
                  determined no applicable cloud-init datasources
     - 'disabled-by-kernel-cmdline': kernel cmdline contained
                  cloud-init=disabled
     - 'enabled-by-kernel-cmdline': kernel cmdline contained
                  cloud-init=enabled
     - 'enabled-by-generator': ds-identify detected possible cloud-init
                  datasources
     - 'enabled-by-sysvinit': enabled by default in SysV init environment

See upstream PR for details: https://github.com/canonical/cloud-init/pull/1663