Add css classes to hyprland special workspaces

[jramrath]

This adds the following css classes to special workspaces in hyprland:

• active (+ correct behavior on monitor focus change)
• visible
• empty

Styling only normal workspaces or only special workspaces is still possible. Example with active:

#workspaces button.active:not(.special) {} /* only normal */
#workspaces button.active.special       {} /* only special */