Use correct worktree when getting permalink to line (#8888)

Previously this code would call `project.visible_worktrees(cx).next`
which might not necessarily return the worktree matching the currently
open file.

What this change does is it adds `get_repo` method on `Project` that
allows us to get the `GitRepository` for the current buffer.

Release Notes:

- Fixed `open permalink to line` not working when multiple folders are
added to the project.

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/project/src/project.rs

@@ -16,6 +16,7 @@ use clock::ReplicaId;
 use collections::{hash_map, BTreeMap, HashMap, HashSet, VecDeque};
 use copilot::Copilot;
 use debounced_delay::DebouncedDelay;
+use fs::repository::GitRepository;
 use futures::{
     channel::mpsc::{self, UnboundedReceiver},
     future::{try_join_all, Shared},
@@ -7302,6 +7303,18 @@ impl Project {
         })
     }
 
+    pub fn get_repo(
+        &self,
+        project_path: &ProjectPath,
+        cx: &AppContext,
+    ) -> Option<Arc<Mutex<dyn GitRepository>>> {
+        self.worktree_for_id(project_path.worktree_id, cx)?
+            .read(cx)
+            .as_local()?
+            .snapshot()
+            .local_git_repo(&project_path.path)
+    }
+
     // RPC message handlers
 
     async fn handle_unshare_project(