gpui: Fix snap_to_window_with_margin when window has client inset (#27330)

Release Notes:

- Fixed popup menu snap to window to leave margin on Linux.

This change to continue #17159 to fix same thing on Linux.

| Before | After |
| -- | -- |
| ![Pasted
image](https://github.com/user-attachments/assets/3129d42c-7253-4a3f-a428-86e2a3df38ff)
|
![image](https://github.com/user-attachments/assets/8dc83377-9df7-45ba-805b-1cfdea612ae0)
|

crates/gpui/src/window.rs

@@ -646,6 +646,7 @@ pub struct Window {
     pending_modifier: ModifierState,
     pub(crate) pending_input_observers: SubscriberSet<(), AnyObserver>,
     prompt: Option<RenderablePromptHandle>,
+    pub(crate) client_inset: Option<Pixels>,
 }
 
 #[derive(Clone, Debug, Default)]
@@ -931,6 +932,7 @@ impl Window {
             pending_modifier: ModifierState::default(),
             pending_input_observers: SubscriberSet::new(),
             prompt: None,
+            client_inset: None,
         })
     }
 
@@ -1387,10 +1389,16 @@ impl Window {
     }
 
     /// When using client side decorations, set this to the width of the invisible decorations (Wayland and X11)
-    pub fn set_client_inset(&self, inset: Pixels) {
+    pub fn set_client_inset(&mut self, inset: Pixels) {
+        self.client_inset = Some(inset);
         self.platform_window.set_client_inset(inset);
     }
 
+    /// Returns the client_inset value by [`Self::set_client_inset`].
+    pub fn client_inset(&self) -> Option<Pixels> {
+        self.client_inset
+    }
+
     /// Returns whether the title bar window controls need to be rendered by the application (Wayland and X11)
     pub fn window_decorations(&self) -> Decorations {
         self.platform_window.window_decorations()