Add more flexibility to cloud-config headers

[AdrienEti]

Is your feature request related to a problem? Please describe.
Currently, it is not possible to execute a cloud-config yaml file if the file does not begin with the header '#cloud-config'.
As a result, it is not possible to execute a cloud-config yaml file with yip along with other headers

Describe the solution you'd like
It can be useful to allow other headers to be executed by yip, for example, Jinja headers used by cloud-init.

Additional context
This request follows issue kairos-io/kairos#1714, which has been resolved (thanks for that), allowing kairos-agent not to return an error if the header does not begin with #cloud-config.
However, it seems that the patch also needs to be applied here; otherwise, yip does not execute the cloud-config file.
I've performed some tests using the same patch that you used for kairos-sdk, rebuilt kairos-agent with the new version of yip, and it works.