to <format>: preserve round float numbers' type (#16016)

- fixes #16011

# Description
`Display` implementation for `f64` omits the decimal part for round
numbers, and by using it we did the same.
This affected:
- conversions to delimited formats: `csv`, `tsv`
- textual formats: `html`, `md`, `text`
- pretty printed `json` (`--raw` was unaffected)
- how single float values are displayed in the REPL

> [!TIP]
> This PR fixes our existing json pretty printing implementation.
> We can likely switch to using serde_json's impl using its
PrettyFormatter which allows arbitrary indent strings.

# User-Facing Changes
- Round trips through `csv`, `tsv`, and `json` preserve the type of
round floats.
- It's always clear whether a number is an integer or a float in the
REPL
  ```nushell
  4 / 2
  # => 2  # before: is this an int or a float?

  4 / 2
  # => 2.0  # after: clearly a float
  ``` 

# Tests + Formatting
Adjusted tests for the new behavior.

- 🟢 toolkit fmt
- 🟢 toolkit clippy
- 🟢 toolkit test
- 🟢 toolkit test stdlib

# After Submitting
N/A

---------

Co-authored-by: Bahex <17417311+Bahex@users.noreply.github.com>

crates/nu-command/tests/commands/histogram.rs

@@ -80,7 +80,7 @@ fn count() {
         "
     ));
 
-    let bit_json = r#"[  {    "bit": 1,    "count": 3,    "quantile": 0.5,    "percentage": "50.00%"  },  {    "bit": 0,    "count": 6,    "quantile": 1,    "percentage": "100.00%"  }]"#;
+    let bit_json = r#"[  {    "bit": 1,    "count": 3,    "quantile": 0.5,    "percentage": "50.00%"  },  {    "bit": 0,    "count": 6,    "quantile": 1.0,    "percentage": "100.00%"  }]"#;
 
     assert_eq!(actual.out, bit_json);
 }