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/editor/src/items.rs

@@ -38,10 +38,14 @@ use text::{BufferId, Selection};
 use theme::{Theme, ThemeSettings};
 use ui::{prelude::*, IconDecorationKind};
 use util::{paths::PathExt, ResultExt, TryFutureExt};
-use workspace::item::{Dedup, ItemSettings, SerializableItem, TabContentParams};
 use workspace::{
     item::{BreadcrumbText, FollowEvent},
     searchable::SearchOptions,
+    OpenVisible,
+};
+use workspace::{
+    item::{Dedup, ItemSettings, SerializableItem, TabContentParams},
+    OpenOptions,
 };
 use workspace::{
     item::{FollowableItem, Item, ItemEvent, ProjectItem},
@@ -1157,7 +1161,15 @@ impl SerializableItem for Editor {
                     }
                     None => {
                         let open_by_abs_path = workspace.update(cx, |workspace, cx| {
-                            workspace.open_abs_path(abs_path.clone(), false, window, cx)
+                            workspace.open_abs_path(
+                                abs_path.clone(),
+                                OpenOptions {
+                                    visible: Some(OpenVisible::None),
+                                    ..Default::default()
+                                },
+                                window,
+                                cx,
+                            )
                         });
                         window.spawn(cx, |mut cx| async move {
                             let editor = open_by_abs_path?.await?.downcast::<Editor>().with_context(|| format!("Failed to downcast to Editor after opening abs path {abs_path:?}"))?;