Improve popup menu to leave some margin with window edges (#17159)

Release Notes:

- Improved popup menu to leave some margin with window edges.

## Updates in GPUI

- gpui: Add `snap_to_window_with_margin` method to `anchored` to support
leave margin to window edges.

## Before

<img width="609" alt="before-snap-to-window 2024-08-30 222506"
src="https://github.com/user-attachments/assets/62bb6791-7c89-4558-9484-5c7b31f5e91e">

## After

<img width="698" alt="snap-to-window1 2024-08-30 222506"
src="https://github.com/user-attachments/assets/51634e79-2a95-42fe-8362-a3c7003648eb">

<img width="622" alt="snap-to-window 2024-08-30 222506"
src="https://github.com/user-attachments/assets/43a865d6-d238-4fdc-ae9d-8160b9ba7953">

crates/gpui/src/geometry.rs

@@ -1836,11 +1836,18 @@ impl Edges<Pixels> {
 
 impl From<f32> for Edges<Pixels> {
     fn from(val: f32) -> Self {
+        let val: Pixels = val.into();
+        val.into()
+    }
+}
+
+impl From<Pixels> for Edges<Pixels> {
+    fn from(val: Pixels) -> Self {
         Edges {
-            top: val.into(),
-            right: val.into(),
-            bottom: val.into(),
-            left: val.into(),
+            top: val,
+            right: val,
+            bottom: val,
+            left: val,
         }
     }
 }