webmin: Move home dir and presets tables into separate pages

[rdmark]

The combination of volumes + home dir + presets at the top of the Webmin landing page adds up to a lot of vertical real estate, easily pushing out the global setting icons and the process control buttons from the viewport.

I think it would make for a better UX if the most critical user flows are visible at a glance when you load up the module. I.e. active shared volumes, available global setting categories, and the state / control of netatalk processes.

Hence, this ticket is about creating separate pages for configuring home dir and presets. These are likely to be uncommonly used features by most of the user base.