Worktree paths in git panel, take 2 (#26047)

Modified version of #25950. We still use worktree paths, but repo paths
with a status that lie outside the worktree are not excluded; instead,
we relativize them by adding `..`. This makes the list in the git panel
match what you'd get from running `git status` (with the repo's worktree
root as the working directory).

- [x] Implement + test new unrelativization logic
- [x] ~~When collecting repositories, dedup by .git abs path, so
worktrees can share a repo at the project level~~ dedup repos at the
repository selector layer, with repos coming from larger worktrees being
preferred
- [x] Open single-file worktree with diff when activating a path not in
the worktree

Release Notes:

- N/A

crates/journal/src/journal.rs

@@ -133,13 +133,31 @@ pub fn new_journal_entry(workspace: &Workspace, window: &mut Window, cx: &mut Ap
                     .await?;
                 new_workspace
                     .update(&mut cx, |workspace, window, cx| {
-                        workspace.open_paths(vec![entry_path], OpenVisible::All, None, window, cx)
+                        workspace.open_paths(
+                            vec![entry_path],
+                            workspace::OpenOptions {
+                                visible: Some(OpenVisible::All),
+                                ..Default::default()
+                            },
+                            None,
+                            window,
+                            cx,
+                        )
                     })?
                     .await
             } else {
                 view_snapshot
                     .update_in(&mut cx, |workspace, window, cx| {
-                        workspace.open_paths(vec![entry_path], OpenVisible::All, None, window, cx)
+                        workspace.open_paths(
+                            vec![entry_path],
+                            workspace::OpenOptions {
+                                visible: Some(OpenVisible::All),
+                                ..Default::default()
+                            },
+                            None,
+                            window,
+                            cx,
+                        )
                     })?
                     .await
             };