Use variable names directly in the format strings (#7906)

# Description

Lint: `clippy::uninlined_format_args`

More readable in most situations.
(May be slightly confusing for modifier format strings
https://doc.rust-lang.org/std/fmt/index.html#formatting-parameters)

Alternative to #7865

# User-Facing Changes

None intended

# Tests + Formatting

(Ran `cargo +stable clippy --fix --workspace -- -A clippy::all -D
clippy::uninlined_format_args` to achieve this. Depends on Rust `1.67`)

crates/nu-command/src/viewers/griddle.rs

@@ -239,7 +239,7 @@ fn create_grid_output(
             Value::string(grid_display.to_string(), call.head)
         } else {
             Value::String {
-                val: format!("Couldn't fit grid into {} columns!", cols),
+                val: format!("Couldn't fit grid into {cols} columns!"),
                 span: call.head,
             }
         }

crates/nu-command/src/viewers/table.rs

@@ -320,7 +320,7 @@ fn handle_table_command(
                 } else {
                     // assume this failed because the table was too wide
                     // TODO: more robust error classification
-                    format!("Couldn't fit table into {} columns!", term_width)
+                    format!("Couldn't fit table into {term_width} columns!")
                 }
             });
 
@@ -1481,7 +1481,7 @@ fn convert_with_precision(val: &str, precision: usize) -> Result<String, ShellEr
             ));
         }
     };
-    Ok(format!("{:.prec$}", val_float, prec = precision))
+    Ok(format!("{val_float:.precision$}"))
 }
 
 fn is_cfg_trim_keep_words(config: &Config) -> bool {
@@ -1696,7 +1696,7 @@ impl Iterator for PagingTableCreator {
                     // assume this failed because the table was too wide
                     // TODO: more robust error classification
                     let term_width = get_width_param(self.width_param);
-                    format!("Couldn't fit table into {} columns!", term_width)
+                    format!("Couldn't fit table into {term_width} columns!")
                 };
                 Some(Ok(msg.as_bytes().to_vec()))
             }