git_ui: Dismiss pickers only on active window (#41320)

Small QOL improvement for branch picker to only dismiss when focus lost
in active window.
This can benefit those who need to switch windows mid branch creation to
fetch correct jira ticket number or etc.

Added `window.is_active_window()` guard in `picker.rs` -> `cancel` event

Release Notes:
- (Let's Git Together) Fixed a behavior where pickers would
automatically close upon the window becoming inactive.

crates/picker/src/picker.rs

@@ -607,7 +607,7 @@ impl<D: PickerDelegate> Picker<D> {
                 self.update_matches(query, window, cx);
             }
             editor::EditorEvent::Blurred => {
-                if self.is_modal {
+                if self.is_modal && window.is_window_active() {
                     self.cancel(&menu::Cancel, window, cx);
                 }
             }
@@ -619,7 +619,9 @@ impl<D: PickerDelegate> Picker<D> {
         let Head::Empty(_) = &self.head else {
             panic!("unexpected call");
         };
-        self.cancel(&menu::Cancel, window, cx);
+        if window.is_window_active() {
+            self.cancel(&menu::Cancel, window, cx);
+        }
     }
 
     pub fn refresh_placeholder(&mut self, window: &mut Window, cx: &mut App) {