Pass Stack ref to Completer::fetch (#12783)

# Description
Adds an additional `&Stack` parameter to `Completer::fetch` so that the
completers don't have to store a `Stack` themselves. I also removed
unnecessary `EngineState`s from the completers, since the same
`EngineState` is available in the `working_set.permanent_state` also
passed to `Completer::fetch`.

crates/nu-cli/src/repl.rs

@@ -389,7 +389,7 @@ fn loop_iteration(ctx: LoopContext) -> (bool, Stack, Reedline) {
         .with_completer(Box::new(NuCompleter::new(
             engine_reference.clone(),
             // STACK-REFERENCE 2
-            Stack::with_parent(stack_arc.clone()),
+            stack_arc.clone(),
         )))
         .with_quick_completions(config.quick_completions)
         .with_partial_completions(config.partial_completions)