Feature request: add custom links on home screen

# Description
- I would like to add custom links to my Umbrel home screen e.g. links to my router web interface, other servers' web interfaces True NAS, etc.
- it would be nice to have some default icons to choose from e.g. router icon, server icon, ... 

# Benefits
- Umbrel OS could now be default hub for the network, where you can get to different places from