Open new windows with a default size and position (#9204)

This PR changes GPUI to open windows with a default size and location,
and to otherwise inherit from their spawning window.

Note: The linux build now crashes on startup.

Release Notes:

- N/A

---------

Co-authored-by: Nathan <nathan@zed.dev>
Co-authored-by: Ezekiel Warren <zaucy@users.noreply.github.com>

crates/gpui/examples/hello_world.rs

@@ -23,18 +23,17 @@ impl Render for HelloWorld {
 
 fn main() {
     App::new().run(|cx: &mut AppContext| {
-        let options = WindowOptions {
-            bounds: WindowBounds::Fixed(Bounds {
-                size: size(px(600.0), px(600.0)).into(),
-                origin: Default::default(),
-            }),
-            center: true,
-            ..Default::default()
-        };
-        cx.open_window(options, |cx| {
-            cx.new_view(|_cx| HelloWorld {
-                text: "World".into(),
-            })
-        });
+        let bounds = Bounds::centered(size(px(600.0), px(600.0)), cx);
+        cx.open_window(
+            WindowOptions {
+                bounds: Some(bounds),
+                ..Default::default()
+            },
+            |cx| {
+                cx.new_view(|_cx| HelloWorld {
+                    text: "World".into(),
+                })
+            },
+        );
     });
 }