Port eww tab (workspace) handling to plsdo

The shell scripts that should be ported are:

hypr-singleton-window: used for launching or navigating to "singleton" windows (I'm not satisfied with the name) - they are bound to a certain tab, and invoking it again navigates to the tab where the window lives, instead of launching another instance of it. May behave unexpectedly if there are multiple windows that share the same name/identifier/whatever.
hypr-workspace: used for navigating to a tab or moving a window to a tab. Maintains the state of tabs in a file that is processed by eww to display the tabs widgets.
hypr-spawnie: I think I had the intention of keeping track of the singleton applications in a widget, while also providing a way to launch those applications by clicking on their icons, sort of like the pinned applications on the windows taskbar. IIRC I had trouble with this because the script would also open a blank terminal window
hypr-scratchpad: also had trouble with this but I don't remember what exactly. Scratchpad terminals would be a nice addition though for one-off tasks like running tests on a project / opening a calculator / etc.

sij1nk / plsdo