Boxes record for smaller Value enum. (#12252)

<!--
if this PR closes one or more issues, you can automatically link the PR
with
them by using one of the [*linking
keywords*](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword),
e.g.
- this PR should close #xxxx
- fixes #xxxx

you can also mention related issues, PRs or discussions!
-->

# Description
<!--
Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.

Description of your pull request goes here. **Provide examples and/or
screenshots** if your changes affect the user experience.
-->
Boxes `Record` inside `Value` to reduce memory usage, `Value` goes from
`72` -> `56` bytes after this change.
# 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 std testing; testing run-tests --path
crates/nu-std"` 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-command/src/network/http/client.rs

@@ -221,7 +221,7 @@ pub fn send_request(
         Value::Record { val, .. } if body_type == BodyType::Form => {
             let mut data: Vec<(String, String)> = Vec::with_capacity(val.len());
 
-            for (col, val) in val {
+            for (col, val) in *val {
                 data.push((col, val.coerce_into_string()?))
             }
 
@@ -335,7 +335,7 @@ pub fn request_add_custom_headers(
 
         match &headers {
             Value::Record { val, .. } => {
-                for (k, v) in val {
+                for (k, v) in &**val {
                     custom_headers.insert(k.to_string(), v.clone());
                 }
             }
@@ -345,7 +345,7 @@ pub fn request_add_custom_headers(
                     // single row([key1 key2]; [val1 val2])
                     match &table[0] {
                         Value::Record { val, .. } => {
-                            for (k, v) in val {
+                            for (k, v) in &**val {
                                 custom_headers.insert(k.to_string(), v.clone());
                             }
                         }

crates/nu-command/src/network/url/build_query.rs

@@ -69,7 +69,7 @@ fn to_url(input: PipelineData, head: Span) -> Result<PipelineData, ShellError> {
             match value {
                 Value::Record { ref val, .. } => {
                     let mut row_vec = vec![];
-                    for (k, v) in val {
+                    for (k, v) in &**val {
                         match v.coerce_string() {
                             Ok(s) => {
                                 row_vec.push((k.clone(), s));