Pinned floating windows

[oatmealine]

Would really appreciate something like Hyprland's pin window rule; making the floating window always stay, regardless of workspace switching, or otherwise "follow" the current workspace.
This would be useful for, for instance, picture-in-picture popout windows, letting you still see them while switching workspaces frequently

[YaLTeR]

Thought I had made an issue already but I haven't, so I made one now: #932