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/clangd_ext.rs

@@ -2,6 +2,7 @@ use anyhow::Context as _;
 use gpui::{App, Context, Entity, Window};
 use language::Language;
 use url::Url;
+use workspace::{OpenOptions, OpenVisible};
 
 use crate::lsp_ext::find_specific_language_server_in_selection;
 
@@ -72,7 +73,7 @@ pub fn switch_source_header(
 
         workspace
             .update_in(&mut cx, |workspace, window, cx| {
-                workspace.open_abs_path(path, false, window, cx)
+                workspace.open_abs_path(path, OpenOptions { visible: Some(OpenVisible::None), ..Default::default() }, window, cx)
             })
             .with_context(|| {
                 format!(