Inject venv environment via the toolchain (#36576)

Instead of manually constructing the venv we now ask the python
toolchain for the relevant information, unifying the approach of vent
inspection

Fixes https://github.com/zed-industries/zed/issues/27350

Release Notes:

- Improved the detection of python virtual environments for terminals
and tasks in remote projects.

crates/util/src/util.rs

@@ -1057,6 +1057,18 @@ pub fn get_system_shell() -> String {
     }
 }
 
+pub fn get_default_system_shell() -> String {
+    #[cfg(target_os = "windows")]
+    {
+        get_windows_system_shell()
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        "/bin/sh".to_string()
+    }
+}
+
 #[derive(Debug)]
 pub enum ConnectionResult<O> {
     Timeout,