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/collab_ui/src/collab_ui.rs

@@ -13,7 +13,7 @@ use call::{report_call_event_for_room, ActiveCall};
 pub use collab_panel::CollabPanel;
 pub use collab_titlebar_item::CollabTitlebarItem;
 use gpui::{
-    actions, point, AppContext, GlobalPixels, Pixels, PlatformDisplay, Size, Task, WindowContext,
+    actions, point, AppContext, DevicePixels, Pixels, PlatformDisplay, Size, Task, WindowContext,
     WindowKind, WindowOptions,
 };
 use panel_settings::MessageEditorSettings;
@@ -97,13 +97,13 @@ fn notification_window_options(
     screen: Rc<dyn PlatformDisplay>,
     window_size: Size<Pixels>,
 ) -> WindowOptions {
-    let notification_margin_width = GlobalPixels::from(16.);
-    let notification_margin_height = GlobalPixels::from(-0.) - GlobalPixels::from(48.);
+    let notification_margin_width = DevicePixels::from(16);
+    let notification_margin_height = DevicePixels::from(-0) - DevicePixels::from(48);
 
     let screen_bounds = screen.bounds();
-    let size: Size<GlobalPixels> = window_size.into();
+    let size: Size<DevicePixels> = window_size.into();
 
-    let bounds = gpui::Bounds::<GlobalPixels> {
+    let bounds = gpui::Bounds::<DevicePixels> {
         origin: screen_bounds.upper_right()
             - point(
                 size.width + notification_margin_width,