Configurable window decorations (#13866)

Introduces the `ZED_WINDOW_DECORATIONS` env variable.

- Not set, defaulting to client-side decorations
- Value is "client": client-side decorations
- Value is "server": server-side decorations

I think it's good to have this escape-hatch next to all possible
detection mechanisms.

Release Notes:

- N/A

crates/workspace/src/workspace.rs

@@ -6491,8 +6491,6 @@ pub fn client_side_decorations(element: impl IntoElement, cx: &mut WindowContext
         cx.set_client_inset(theme::CLIENT_SIDE_DECORATION_SHADOW);
     }
 
-    println!("decorations: {:?}", decorations);
-
     struct GlobalResizeEdge(ResizeEdge);
     impl Global for GlobalResizeEdge {}