Add OpenExcerptsSplit (#8574)

I would like to keep diagnostics open on one side, and process them on
the other.


Release Notes:

- Added `editor::OpenExcerptsSplit` (bound to `cmd-k enter`) to open the
selected excerpts in the adjacent pane
- vim: Added `ctrl-w d`, `ctrl-w shift-d` and `ctrl-w space` for
`editor::GoTo{,Type}Definition` and `editor::OpenExcerptsSplit`

crates/auto_update/src/auto_update.rs

@@ -242,7 +242,7 @@ fn view_release_notes_locally(workspace: &mut Workspace, cx: &mut ViewContext<Wo
                                 Some(tab_description),
                                 cx,
                             );
-                            workspace.add_item(Box::new(view.clone()), cx);
+                            workspace.add_item_to_active_pane(Box::new(view.clone()), cx);
                             cx.notify();
                         })
                         .log_err();