Ability to manually enable Kerberos security

Provide an option for users that want to enable Kerberos in the cluster via Ambari but do not want any automation. With this option, ambari will not require any access to the KDC, will not install kerberos clients, will not attempt to generate any principals or keytabs and will not distribute any keytabs. Keytab regeneration will not be available, and when there are changes to the cluster (add service, add/remove/change host), the user is responsible for creating principals and making sure the appropriate keytabs are in place on the host for proper cluster function (although Ambari should handle updating any configs).

Effectively, this above option provides a manual Kerberos option for users that are looking to have the similar "hands-off" ambari kerberos experience of 1.7.0 or earlier.

On the Kerberos Wizard, provide an option (below Existing MIT KDC and Existing Active Directory):

[ ] Manage Kerberos manually

Which will send the wizard thru a path that does not prompt for KDC information, or attempt to install clients or create principals/keytabs. The user should have a chance to Configure Identities as part of the wizard and the wizard will push the configs, performs restarts, etc. Users should have an option to download a CSV of principals, keytabs, hosts, locations, permissions, ownership.

Semi-related: as part of this work, for users that will use kerberos automation, expose an option to not install Kerberos clients.