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-protocol/src/value/format.rs

@@ -1,16 +0,0 @@
-use std::fmt::Display;
-
-/// A f64 wrapper that formats whole numbers with a decimal point.
-pub struct ObviousFloat(pub f64);
-
-impl Display for ObviousFloat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let val = self.0;
-        // This serialises these as 'nan', 'inf' and '-inf', respectively.
-        if val.round() == val && val.is_finite() {
-            write!(f, "{}.0", val)
-        } else {
-            write!(f, "{}", val)
-        }
-    }
-}

crates/nu-protocol/src/value/mod.rs

@@ -8,7 +8,6 @@ mod range;
 #[cfg(test)]
 mod test_derive;
 
-pub mod format;
 pub mod record;
 pub use custom_value::CustomValue;
 pub use duration::*;
@@ -29,7 +28,7 @@ use chrono::{DateTime, Datelike, Duration, FixedOffset, Local, Locale, TimeZone}
 use chrono_humanize::HumanTime;
 use fancy_regex::Regex;
 use nu_utils::{
-    SharedCow, contains_emoji,
+    ObviousFloat, SharedCow, contains_emoji,
     locale::{LOCALE_OVERRIDE_ENV_VAR, get_system_locale_string},
 };
 use serde::{Deserialize, Serialize};
@@ -939,7 +938,7 @@ impl Value {
         match self {
             Value::Bool { val, .. } => val.to_string(),
             Value::Int { val, .. } => val.to_string(),
-            Value::Float { val, .. } => val.to_string(),
+            Value::Float { val, .. } => ObviousFloat(*val).to_string(),
             Value::Filesize { val, .. } => config.filesize.format(*val).to_string(),
             Value::Duration { val, .. } => format_duration(*val),
             Value::Date { val, .. } => match &config.datetime_format.normal {

crates/nu-protocol/src/value/range.rs

@@ -307,10 +307,8 @@ mod int_range {
 }
 
 mod float_range {
-    use crate::{
-        IntRange, Range, ShellError, Signals, Span, Value, ast::RangeInclusion,
-        format::ObviousFloat,
-    };
+    use crate::{IntRange, Range, ShellError, Signals, Span, Value, ast::RangeInclusion};
+    use nu_utils::ObviousFloat;
     use serde::{Deserialize, Serialize};
     use std::{cmp::Ordering, fmt::Display, ops::Bound};