Request: add a way to toggle ghost icons for `/iconsasui 1`

`/iconsasui 1` is a whole package of icon changes, one of them is that building ghosts also display an icon. The request is to make this toggleable (ideally it would become completely separate and available for `/iconsasui 0` as well, following icon rules of that mode, but just toggling it off for `/iconsasui 1` would be an improvement).

Edit: reminder that this also applies to the minimap.

Start by tracing the `/iconsasui 1` command and the existing building-ghost icon behavior, including the minimap case mentioned in the request. Determine how the toggle should interact with `/iconsasui 0`; done means ghost icons can be independently disabled for mode 1 and the minimap follows the selected behavior.

Written by the indexing model from the issue text.