Try to preserve the ordering of elements in from toml (#13045)

# Description

Enable the `preserve_order` feature of the `toml` crate to preserve the
ordering of elements when converting from/to toml.

Additionally, use `to_string_pretty()` instead of `to_string()` in `to
toml`. This displays arrays on multiple lines instead of one big single
line. I'm not sure if this one is a good idea or not... Happy to remove
this from this PR if it's not.

# User-Facing Changes
The order of elements will be different when using `from toml`. The
formatting of arrays will also be different when using `to toml`. For
example:

- before
```
❯ "foo=1\nbar=2\ndoo=3" | from toml
╭─────┬───╮
│ bar │ 2 │
│ doo │ 3 │
│ foo │ 1 │
╰─────┴───╯
❯ {a: [a b c d]} | to toml
a = ["a", "b", "c", "d"]
```
- after
```
❯ "foo=1\nbar=2\ndoo=3" | from toml
╭─────┬───╮
│ foo │ 1 │
│ bar │ 2 │
│ doo │ 3 │
╰─────┴───╯
❯ {a: [a b c d]} | to toml
a = [
    "a",
    "b",
    "c",
    "d",
]
```

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🔴 `toolkit test`
- ⚫ `toolkit test stdlib`

# After Submitting
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Cargo.lock

@@ -6068,6 +6068,7 @@ version = "0.8.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e9dd1545e8208b4a5af1aa9bbd0b4cf7e9ea08fabc5d0a5c67fcaafa17433aa3"
 dependencies = [
+ "indexmap",
  "serde",
  "serde_spanned",
  "toml_datetime",

crates/nu-command/Cargo.toml

@@ -86,7 +86,7 @@ sysinfo = { workspace = true }
 tabled = { workspace = true, features = ["color"], default-features = false }
 terminal_size = { workspace = true }
 titlecase = { workspace = true }
-toml = { workspace = true }
+toml = { workspace = true, features = ["preserve_order"]}
 unicode-segmentation = { workspace = true }
 ureq = { workspace = true, default-features = false, features = ["charset", "gzip", "json", "native-tls"] }
 url = { workspace = true }

crates/nu-command/src/formats/to/toml.rs

@@ -24,7 +24,7 @@ impl Command for ToToml {
         vec![Example {
             description: "Outputs an TOML string representing the contents of this record",
             example: r#"{foo: 1 bar: 'qwe'} | to toml"#,
-            result: Some(Value::test_string("bar = \"qwe\"\nfoo = 1\n")),
+            result: Some(Value::test_string("foo = 1\nbar = \"qwe\"\n")),
         }]
     }
 
@@ -103,7 +103,7 @@ fn toml_into_pipeline_data(
     value_type: Type,
     span: Span,
 ) -> Result<PipelineData, ShellError> {
-    match toml::to_string(&toml_value) {
+    match toml::to_string_pretty(&toml_value) {
         Ok(serde_toml_string) => Ok(Value::string(serde_toml_string, span).into_pipeline_data()),
         _ => Ok(Value::error(
             ShellError::CantConvert {