Add login link option to ispc cli tool

What about adding the command: ispc user login <username> [ttl_minutes] - Generate a one-time autologin token for the ISPConfig user <username>.

Many tools such a Drupal, Wordpress and even plesk offer to create a login link from the cli.

Since the user already needs root access to be able to read the ispconfig config files I would state that this does not add serious additional risk. A user that can call this would also be able to directly change the password hash in the database.

I was tempted to combine this with the password reset flow, however there a new password is mailed... so not useful for a quick login.

I have a working prototype in the linked MR.