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/conversions/into/cell_path.rs

@@ -98,7 +98,7 @@ fn into_cell_path(call: &Call, input: PipelineData) -> Result<PipelineData, Shel
     match input {
         PipelineData::Value(value, _) => Ok(value_to_cell_path(&value, head)?.into_pipeline_data()),
         PipelineData::ListStream(stream, ..) => {
-            let list: Vec<_> = stream.collect();
+            let list: Vec<_> = stream.into_iter().collect();
             Ok(list_to_cell_path(&list, head)?.into_pipeline_data())
         }
         PipelineData::ExternalStream { span, .. } => Err(ShellError::OnlySupportsThisInputType {

crates/nu-command/src/conversions/into/value.rs

@@ -81,7 +81,7 @@ impl Command for IntoValue {
             display_as_filesizes,
             span,
         }
-        .into_pipeline_data(ctrlc)
+        .into_pipeline_data(span, ctrlc)
         .set_metadata(metadata))
     }
 }