Expand workspace-specific icon formatting

[JakobPogacnikSouvent]

Right now waybar supports workspace specific icons, but it is not possible to specify different default, active, empty and visible icons for a specific workspace. Thus it is impossible to produce a workspaces module like this:

I think that expanding workspace-specific options for icon formatting would not be difficult to implement while increasing customization options and keeping backwards compatibility.

The above example could, for instance, be produced with something like

"format": "{icon}",
"format-icons": {
  "default": "◉",
  "empty": "○",
  "persistent": "◉",
  "visible": "●",
  "1": "󰲠",
  "1-empty": "󰲡",
  "2": "󰲢",
  "2-empty": "󰲣",
  ...
},

by adding the following lines to the Workspace::selectIcon method

if (isEmpty()) {
  auto emptyNamedIconIt = icons_map.find(name() + "-empty");
  if (emptyNamedIconIt != icons_map.end()) {
    return emptyNamedIconIt->second;
  }
}

I am interested to know if such a feature would be relevant to waybar users?