uyuniadm install with pre-existing volumes

[rjmateus]

A valid scenario is to call the install and the volumes already exists. This is particular important in podman scenarios where we could uninstall without removing the volumes, or move the volumes to a different VM.

We must support calling the mgradm install podman FQDN.

With this call we must:

• We should detect that the volumes already exists, and print a warning message that the initial configuration parameter will be ignored
• Do not call the creat first user API method or if calling it detect that the first user was already set and do not finish with error.

We can call the set-up script, since it's protected at the volumes level with a check file.