feature: "Only show active spaces"

[lxsavage]

Implemented "Only show active spaces" as a option in preferences which will hide all non-active space numbers from showing on the menubar display.

This button gets auto-disabled when the "Rectangles" style is selected since it would just end up showing a singular rectangle for each monitor that does not convey any information.

I primarily wrote this change since the notch on Apple Silicon iterations of the MacBook Pro means that there is very limited menu bar icon real estate that the inactive desktop numbers/icons would potentially completely cover if they can even fit on the menu bar in the first place (in the case of having many virtual desktops open).

This PR would address #14, #23

Screenshots

Note: the virtual desktop configuration I have in these screenshots is 9 virtual desktops on the left monitor and one on the right monitor. In addition to this, I have the JankyBorders app active so ignore the blue border around the preference window.

Previous behavior (disabling newly-added checkbox "Only show active spaces")

New behavior

Disabled when "Rectangles" style is chosen

[Artawower]

Is there any chance that this pull request will be merged?