Log warning message when cloud config is not gzipped, multipart mime or plaintext

This is an improved version of #219.

Testing

[x] New unit tests pass

[x] Existing test suite triggers new logging when running a VM test (all cloud config used in the acceptance tests is malformed and will trigger this new check)


hestraVm_createWithMutipleDisks TF_LOG=trace make testacc 2>&1 | grep WARNING
2022/12/15 11:26:23 [WARNING] cloud config does not start with required text `#cloud-config`.
2022/12/15 11:26:23 [WARNING] Validate that your configuration is well formed according to the documentation (https://cloudinit.readthedocs.io/en/latest/topics/format.html).



@4censord since you wanted this to cover gzipped and multipart mime please give this a look. To do this in an extremely robust way would be quite a bit of work, so my goal was to cover what the cloudinit terraform provider renders.

vatesfr / terraform-provider-xenorchestra

Log warning message when cloud config is not gzipped, multipart mime or plaintext #224

Testing