Allow task context providers to access project env (#17964)

Closes #13106

Release Notes:

- Task context providers now have access to the local shell environment,
allowing local rust tool installations to work

Before:
<img width="1136" alt="Screenshot 2024-09-17 at 22 09 38"
src="https://github.com/user-attachments/assets/7d6c5606-4820-4f6f-92d1-c3d314b9ab42">

After:
<img width="1136" alt="Screenshot 2024-09-17 at 22 09 58"
src="https://github.com/user-attachments/assets/a962e607-15f5-44ce-b53e-a0dbe135f2d8">

crates/languages/src/python.rs

@@ -1,5 +1,6 @@
 use anyhow::Result;
 use async_trait::async_trait;
+use collections::HashMap;
 use gpui::AppContext;
 use gpui::AsyncAppContext;
 use language::{ContextProvider, LanguageServerName, LspAdapter, LspAdapterDelegate};
@@ -215,6 +216,7 @@ impl ContextProvider for PythonContextProvider {
         &self,
         variables: &task::TaskVariables,
         _location: &project::Location,
+        _: Option<&HashMap<String, String>>,
         _cx: &mut gpui::AppContext,
     ) -> Result<task::TaskVariables> {
         let python_module_name = python_module_name_from_relative_path(