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/tests/commands/math/sum.rs

@@ -45,7 +45,7 @@ fn compute_sum_of_individual_row() -> Result<(), String> {
     for (column_name, expected_value) in answers_for_columns {
         let actual = nu!(
             cwd: "tests/fixtures/formats/",
-            format!("open sample-ps-output.json | select {} | math sum | get {}", column_name, column_name)
+            format!("open sample-ps-output.json | select {column_name} | math sum | get {column_name}")
         );
         let result =
             f64::from_str(&actual.out).map_err(|_| String::from("Failed to parse float."))?;
@@ -66,7 +66,7 @@ fn compute_sum_of_table() -> Result<(), String> {
     for (column_name, expected_value) in answers_for_columns {
         let actual = nu!(
             cwd: "tests/fixtures/formats/",
-            format!("open sample-ps-output.json | select cpu mem virtual | math sum | get {}", column_name)
+            format!("open sample-ps-output.json | select cpu mem virtual | math sum | get {column_name}")
         );
         let result =
             f64::from_str(&actual.out).map_err(|_| String::from("Failed to parse float."))?;

crates/nu-command/tests/commands/platform/kill.rs

@@ -3,7 +3,7 @@ use nu_test_support::nu;
 #[test]
 fn test_kill_invalid_pid() {
     let pid = i32::MAX;
-    let actual = nu!(format!("kill {}", pid));
+    let actual = nu!(format!("kill {pid}"));
 
     assert!(actual.err.contains("process didn't terminate successfully"));
 }

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

@@ -97,7 +97,7 @@ mod columns {
 
         let actual = nu!(
             cwd: ".",
-            format!("{} | roll right --by 3 --cells-only | columns | str join '-' ", four_bitstring)
+            format!("{four_bitstring} | roll right --by 3 --cells-only | columns | str join '-' ")
         );
 
         assert_eq!(actual.out, expected_value.1);
@@ -142,12 +142,11 @@ mod columns {
         "#,
         );
         println!(
-            "{} | roll left --by 3 | {}",
-            bitstring_as_nu_row_pipeline, nu_row_literal_bitstring_to_decimal_value_pipeline
+            "{bitstring_as_nu_row_pipeline} | roll left --by 3 | {nu_row_literal_bitstring_to_decimal_value_pipeline}"
         );
         nu!(
             cwd: ".",
-            format!("{} | roll left --by 3 | {}", bitstring_as_nu_row_pipeline, nu_row_literal_bitstring_to_decimal_value_pipeline)
+            format!("{bitstring_as_nu_row_pipeline} | roll left --by 3 | {nu_row_literal_bitstring_to_decimal_value_pipeline}")
         ).out
     }
 

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

@@ -16,7 +16,7 @@ fn writes_out_csv() {
         );
 
         let actual = file_contents(expected_file);
-        println!("{}", actual);
+        println!("{actual}");
         assert!(actual.contains("nu,0.14,A new type of shell,MIT,2018"));
     })
 }
@@ -52,7 +52,7 @@ fn save_append_will_create_file_if_not_exists() {
         );
 
         let actual = file_contents(expected_file);
-        println!("{}", actual);
+        println!("{actual}");
         assert_eq!(actual, "hello");
     })
 }
@@ -78,7 +78,7 @@ fn save_append_will_not_overwrite_content() {
         );
 
         let actual = file_contents(expected_file);
-        println!("{}", actual);
+        println!("{actual}");
         assert_eq!(actual, "hello world");
     })
 }

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

@@ -16,10 +16,9 @@ fn sources_also_files_under_custom_lib_dirs_path() {
             "config.toml",
             &format!(
                 r#"
-                lib_dirs = ["{}"]
+                lib_dirs = ["{library_path}"]
                 skip_welcome_message = true
-            "#,
-                library_path
+            "#
             ),
         )]);
 
@@ -151,7 +150,7 @@ fn can_source_dynamic_path() {
 
         sandbox.with_files(vec![FileWithContent(foo_file, "echo foo")]);
 
-        let cmd = format!("let file = `{}`; source-env $file", foo_file);
+        let cmd = format!("let file = `{foo_file}`; source-env $file");
         let actual = nu!(cwd: dirs.test(), &cmd);
 
         assert_eq!(actual.out, "foo");

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

@@ -19,7 +19,7 @@ fn zips_two_tables() {
     Playground::setup("zip_test_1", |dirs, nu| {
         nu.with_files(vec![FileWithContent(
             "zip_test.nu",
-            &format!("{}\n", ZIP_POWERED_TEST_ASSERTION_SCRIPT),
+            &format!("{ZIP_POWERED_TEST_ASSERTION_SCRIPT}\n"),
         )]);
 
         let actual = nu!(