Switch to using subprocess::shell (#1264)

* Switch to using `shell`

Switch to using the shell for subprocess to enable more natural shelling out.

* Update external.rs

* This is a test with .shell() for external

* El pollo loco's PR

* co co co

* Attempt to fix windows

* Fmt

* Less is more?

Co-authored-by: Andrés N. Robalino <andres@androbtech.com>

crates/nu-test-support/src/lib.rs

@@ -14,6 +14,16 @@ pub fn pipeline(commands: &str) -> String {
         .to_string()
 }
 
+pub fn shell_os_paths() -> Vec<std::path::PathBuf> {
+    let mut original_paths = vec![];
+
+    if let Some(paths) = std::env::var_os("PATH") {
+        original_paths = std::env::split_paths(&paths).collect::<Vec<_>>();
+    }
+
+    original_paths
+}
+
 #[cfg(test)]
 mod tests {
     use super::pipeline;