Create new API endpoints for exposing stack and stack service kerberos descriptors. These endpoints will provide the static descriptors which are defined in the stack definition and will be immutable.
There will be at most 1 descriptor for both the stack and each stack service.
Therefore, it doesn't make sense to add a kerberos_descriptor sub-resource since there will be at most one instance.
Instead, a new "artifacts" endpoint is being introduced.
The kerberos descriptor will be an artifact instance.
To obtain the kerberos descriptor for the HDP 2.2 stack:
To obtain the kerberos descriptor for the HDP 2.2 HDFS service: