gpui: Persist window bounds and display when detaching a workspace session (#45201)
Closes #41246 #45092
Release Notes:
- N/A
**Root Cause**:
Empty local workspaces returned `DetachFromSession` from
`serialize_workspace_location()`, and the `DetachFromSession` handler
only cleared the session_id **without saving window bounds**.
**Fix Applied**:
Modified the `DetachFromSession` handler to save window bounds via
`set_window_open_status()`:
```rust
WorkspaceLocation::DetachFromSession => {
let window_bounds = SerializedWindowBounds(window.window_bounds());
let display = window.display(cx).and_then(|d| d.uuid().ok());
window.spawn(cx, async move |_| {
persistence::DB
.set_window_open_status(database_id, window_bounds, display.unwrap_or_default())
.await.log_err();
persistence::DB.set_session_id(database_id, None).await.log_err();
})
}
```
**Recording**:
https://github.com/user-attachments/assets/2b6564d4-4e1b-40fe-943b-147296340aa7
4f87822133