Parse minimal yaml instead of raw bash script

[andywaltlova]

HMS-1994

• The worker shall receive the data in a playbook-like format and use insights-client to verify the signature
• The worker verifies that nobody has tampered with the contents of the bash script
  • Done similarly like for rhc-worker-playbook
• Prepend all variables located under /vars/content_vars with RHC_WORKER_* and set them in the unix environment
• Include a go-yaml library in the project to process the incoming yaml.

[andywaltlova]

Current signed-bash-script file is not signed so the worker fails and in logs it can be seen that the yaml is invalid, question is what to do in that case, what should be content of the uploaded message?

If I used one of the existing playbooks that are used by insights (and change the struct for expected yaml), then the validation passes.