Add workspace_overview_is_open function; put in a utils::quirks mod

This is increasingly not just related to screencopy, so it's weird to
add there. I don't see any other module that fits, so add one called
"quirks" (like the Linux kernel uses for device-specific handling in
generic drives).

src/utils/mod.rs

@@ -5,6 +5,7 @@ pub(crate) use self::ids::id_gen;
 pub mod geometry;
 pub mod iced;
 pub mod prelude;
+pub mod quirks;
 pub mod rlimit;
 pub mod screenshot;
 pub mod tween;