Replace references to "exwayland" with "satellite"

Exwayland was the original working name for the project, but satellite
is way cooler.

src/xstate/mod.rs

@@ -213,7 +213,7 @@ impl XState {
                 window: self.wm_window,
                 property: self.atoms.net_wm_name,
                 r#type: x::ATOM_STRING,
-                data: b"exwayland wm",
+                data: b"xwayland-satellite",
             })
             .unwrap();