Feature: Add Machine Troubleshooting
Fixes up the add machine workflows.
- The user should be able to specify an SSH port
- The user should not be forced to sync their users between servers.
- Cockpit should be able to configure cloud-user style machines, where there are no individual admin logins.
- The user should be able to recover from a host key change, but should not be able to click through.
- The user should be able to fix authentication problems, without readding a machine.
- It should be simple to Set up key based login
