gtk4: Use GtkPicture instead of GtkImage for unit icons
With the properties of GtkImage in gtk4, they are not feasible type for the unit icons we have. Rearrange code to use GtkPicture instead (I've already had initial success with that - unit icons really show up that way)
Depends (textual dependency only) on #44905
With the properties of GtkImage in gtk4, they are not feasible type for the unit icons we have. Rearrange code to use GtkPicture instead (I've already had initial success with that - unit icons really show up that way)