Support @file on _userdata update

[bchatelard]

[QuentinPerez]

Hi @bchatelard,

@file is already supported,

./scw _userdata 8cc2d32c-5444-4998-81e9-964134700ba7 CLOUD-INIT=@cloud-init.yml

./scw _userdata 8cc2d32c-5444-4998-81e9-964134700ba7 CLOUD-INIT
#cloud-config

hostname: "coreos"

coreos:
  units:
    - name: runcmd.service
      command: start
      content: |
        [Unit]
        Description=Mark as booted

        [Service]
        Type=oneshot
        ExecStart=/bin/sh -c "curl http://169.254.42.42/state -X PATCH -d '{\"state_detail\": \"booted\"}' -H 'Content-Type: application/json'"

[moul]

@bchatelard tested with @~/path/to/file

[QuentinPerez]

Fixed with the PR #332