Rename all?, any? and empty? (#6464)

Rename `all?`, `any?` and `empty?` to `all`, `any` and `is-empty` for sake of simplicity and consistency.

- More understandable for newcomers, that these commands are no special to others.
- `?` syntax did not really aprove readability. For me it made it worse.
- We can reserve `?` syntax for any other nushell feature.

src/tests/test_parser.rs

@@ -205,7 +205,7 @@ fn equals_separates_long_flag() -> TestResult {
 fn let_env_expressions() -> TestResult {
     let env = HashMap::from([("VENV_OLD_PATH", "Foobar"), ("Path", "Quux")]);
     run_test_with_env(
-        r#"let-env Path = if (env | any? name == VENV_OLD_PATH) { $env.VENV_OLD_PATH } else { $env.Path }; echo $env.Path"#,
+        r#"let-env Path = if (env | any name == VENV_OLD_PATH) { $env.VENV_OLD_PATH } else { $env.Path }; echo $env.Path"#,
         "Foobar",
         &env,
     )