lookup closures/blockids and get content in config flatten (#14635)

# Description

This PR continues to tweak `config flatten` by looking up the closures
and block_ids and extracts the content into the produced record.

Example

![image](https://github.com/user-attachments/assets/99a9db54-e477-40b2-8468-bbadcf0aa5b7)


# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` to run the
tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->

crates/nu-utils/src/flatten_json.rs

@@ -227,9 +227,6 @@ impl<'a> JsonFlattener<'a> {
         if filtered_key.contains(".Record.val") {
             filtered_key = filtered_key.replace(".Record.val", "");
         }
-        if filtered_key.contains(".Closure.val") {
-            filtered_key = filtered_key.replace(".Closure.val", "");
-        }
         if filtered_key.contains(".List.vals") {
             filtered_key = filtered_key.replace(".List.vals", "");
         }
@@ -239,9 +236,14 @@ impl<'a> JsonFlattener<'a> {
         if filtered_key.contains(".Bool.val") {
             filtered_key = filtered_key.replace(".Bool.val", "");
         }
-        if filtered_key.contains(".block_id") {
-            filtered_key = filtered_key.replace(".block_id", "");
-        }
+        // For now, let's skip replacing these because they tell us which
+        // numbers are closures and blocks which is useful for extracting the content
+        // if filtered_key.contains(".Closure.val") {
+        //     filtered_key = filtered_key.replace(".Closure.val", "");
+        // }
+        // if filtered_key.contains(".block_id") {
+        //     filtered_key = filtered_key.replace(".block_id", "");
+        // }
         filtered_key
     }
 }