collab ui: Fix notification windows on external monitors (#9817)

Sharing a project displays a notification (window) on every screen.
Previously there was an issue with the positioning of windows on all
screens except the primary screen.

As you can see here:


![image](https://github.com/zed-industries/zed/assets/53836821/314cf367-8c70-4e8e-bc4a-dcbb99cb4f71)

Now:


![image](https://github.com/zed-industries/zed/assets/53836821/42af9ef3-8af9-453a-ad95-147b5f9d90ba)

@mikayla-maki and I also decided to refactor the `WindowOptions` a bit. 
Previously you could specify bounds which controlled the positioning and
size of the window in the global coordinate space, while also providing
a display id (which screen to show the window on). This can lead to
unusual behavior because you could theoretically specify a global bound
which does not even belong to the display id which was provided.

Therefore we changed the api to this:
```rust
struct WindowOptions {
    /// The bounds of the window in screen coordinates
    /// None -> inherit, Some(bounds) -> set bounds.
    pub bounds: Option<Bounds<DevicePixels>>,

    /// The display to create the window on, if this is None,
    /// the window will be created on the main display
    pub display_id: Option<DisplayId>,
}
```

This lets you specify a display id, which maps to the screen where the
window should be created and bounds relative to the upper left of the
screen.

Release Notes:

- Fixed positioning of popup windows (e.g. when sharing a project) when
using multiple external displays.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/gpui/src/platform.rs

@@ -23,9 +23,9 @@ mod windows;
 
 use crate::{
     Action, AnyWindowHandle, AsyncWindowContext, BackgroundExecutor, Bounds, DevicePixels,
-    DispatchEventResult, Font, FontId, FontMetrics, FontRun, ForegroundExecutor, GlobalPixels,
-    GlyphId, Keymap, LineLayout, Pixels, PlatformInput, Point, RenderGlyphParams,
-    RenderImageParams, RenderSvgParams, Scene, SharedString, Size, Task, TaskLabel, WindowContext,
+    DispatchEventResult, Font, FontId, FontMetrics, FontRun, ForegroundExecutor, GlyphId, Keymap,
+    LineLayout, Pixels, PlatformInput, Point, RenderGlyphParams, RenderImageParams,
+    RenderSvgParams, Scene, SharedString, Size, Task, TaskLabel, WindowContext,
 };
 use anyhow::Result;
 use async_task::Runnable;
@@ -152,7 +152,7 @@ pub trait PlatformDisplay: Send + Sync + Debug {
     fn uuid(&self) -> Result<Uuid>;
 
     /// Get the bounds for this display
-    fn bounds(&self) -> Bounds<GlobalPixels>;
+    fn bounds(&self) -> Bounds<DevicePixels>;
 }
 
 /// An opaque identifier for a hardware display
@@ -168,7 +168,7 @@ impl Debug for DisplayId {
 unsafe impl Send for DisplayId {}
 
 pub(crate) trait PlatformWindow: HasWindowHandle + HasDisplayHandle {
-    fn bounds(&self) -> Bounds<GlobalPixels>;
+    fn bounds(&self) -> Bounds<DevicePixels>;
     fn is_maximized(&self) -> bool;
     fn is_minimized(&self) -> bool;
     fn content_size(&self) -> Size<Pixels>;
@@ -508,8 +508,9 @@ pub trait InputHandler: 'static {
 /// The variables that can be configured when creating a new window
 #[derive(Debug)]
 pub struct WindowOptions {
+    /// The bounds of the window in screen coordinates.
     /// None -> inherit, Some(bounds) -> set bounds
-    pub bounds: Option<Bounds<GlobalPixels>>,
+    pub bounds: Option<Bounds<DevicePixels>>,
 
     /// The titlebar configuration of the window
     pub titlebar: Option<TitlebarOptions>,
@@ -529,7 +530,8 @@ pub struct WindowOptions {
     /// Whether the window should be movable by the user
     pub is_movable: bool,
 
-    /// The display to create the window on
+    /// The display to create the window on, if this is None,
+    /// the window will be created on the main display
     pub display_id: Option<DisplayId>,
 }
 
@@ -537,7 +539,7 @@ pub struct WindowOptions {
 #[derive(Debug)]
 pub(crate) struct WindowParams {
     ///
-    pub bounds: Bounds<GlobalPixels>,
+    pub bounds: Bounds<DevicePixels>,
 
     /// The titlebar configuration of the window
     pub titlebar: Option<TitlebarOptions>,
@@ -552,7 +554,6 @@ pub(crate) struct WindowParams {
 
     pub show: bool,
 
-    /// The display to create the window on
     pub display_id: Option<DisplayId>,
 }
 
@@ -599,10 +600,6 @@ pub enum WindowKind {
     PopUp,
 }
 
-/// Platform level interface
-/// bounds: Bounds<GlobalPixels>
-/// fullscreen: bool
-
 /// The appearance of the window, as defined by the operating system.
 ///
 /// On macOS, this corresponds to named [`NSAppearance`](https://developer.apple.com/documentation/appkit/nsappearance)