python: Look for local venvs in all directories between root of the worktree and current pyproject.toml (#37037)

cc @michael-ud - if you can build Zed, I'd appreciate it if you could
give this a go with your project. Otherwise I can provide a link to
download of current nightly via an e-mail for you to try out (if you
want).
This change will land in Preview (if merged) on next Wednesday and then
it'll be in Stable a week after that.
Related to: #20402
Release Notes:

- python: Zed now searches for virtual environments in intermediate
directories between a root of the worktree and the location of
pyproject.toml applicable to the currently focused file.

crates/project/src/project_tests.rs

@@ -9189,13 +9189,14 @@ fn python_lang(fs: Arc<FakeFs>) -> Arc<Language> {
         async fn list(
             &self,
             worktree_root: PathBuf,
-            subroot_relative_path: Option<Arc<Path>>,
+            subroot_relative_path: Arc<Path>,
             _: Option<HashMap<String, String>>,
         ) -> ToolchainList {
             // This lister will always return a path .venv directories within ancestors
             let ancestors = subroot_relative_path
-                .into_iter()
-                .flat_map(|path| path.ancestors().map(ToOwned::to_owned).collect::<Vec<_>>());
+                .ancestors()
+                .map(ToOwned::to_owned)
+                .collect::<Vec<_>>();
             let mut toolchains = vec![];
             for ancestor in ancestors {
                 let venv_path = worktree_root.join(ancestor).join(".venv");

crates/project/src/toolchain_store.rs

@@ -389,12 +389,7 @@ impl LocalToolchainStore {
             cx.background_spawn(async move {
                 Some((
                     toolchains
-                        .list(
-                            worktree_root,
-                            Some(relative_path.path.clone())
-                                .filter(|_| *relative_path.path != *Path::new("")),
-                            project_env,
-                        )
+                        .list(worktree_root, relative_path.path.clone(), project_env)
                         .await,
                     relative_path.path,
                 ))