Add dwl/tags option to show only active tags

[Ty3uK]

Not an experienced C++ developer at all, will be glad to hear any advice 🙏 Generally, it's like sway/workspaces behavior.

[bitterhalt]

Would it be possible to have similar feature in River tags?

[thetwistedlogic]

Would it be possible to have similar feature in River tags?

Just implemented this over here: https://github.com/Alexays/Waybar/pull/3823