ListStream touchup (#12524)

# Description

Does some misc changes to `ListStream`:
- Moves it into its own module/file separate from `RawStream`.
- `ListStream`s now have an associated `Span`.
- This required changes to `ListStreamInfo` in `nu-plugin`. Note sure if
this is a breaking change for the plugin protocol.
- Hides the internals of `ListStream` but also adds a few more methods.
- This includes two functions to more easily alter a stream (these take
a `ListStream` and return a `ListStream` instead of having to go through
the whole `into_pipeline_data(..)` route).
  -  `map`: takes a `FnMut(Value) -> Value`
  - `modify`: takes a function to modify the inner stream.

crates/nu-command/src/random/dice.rs

@@ -78,10 +78,7 @@ fn dice(
         Value::int(thread_rng.gen_range(1..sides + 1) as i64, span)
     });
 
-    Ok(PipelineData::ListStream(
-        ListStream::from_stream(iter, engine_state.ctrlc.clone()),
-        None,
-    ))
+    Ok(ListStream::new(iter, span, engine_state.ctrlc.clone()).into())
 }
 
 #[cfg(test)]