add layout crate with resize handle

src/lib.rs

@@ -10,6 +10,9 @@ pub use gpui_native_core::*;
 #[cfg(feature = "data")]
 pub use gpui_native_data as data;
 
+#[cfg(feature = "layout")]
+pub use gpui_native_layout as layout;
+
 use gpui::App;
 
 /// Initializes the framework.