update format signature to allow record to be passed in (#9898)

# Description

This PR updates the signature of `format` to allow records to be passed
in.

Closes #9897 

### Before
```nushell
{name: Downloads} | format "{name}"

  × Command does not support record<name: string> input.
   ╭─[entry #12:1:1]
 1 │ {name: Downloads} | format "{name}"
   ·                       ───┬──
   ·                          ╰── command doesn't support record<name: string> input
   ╰────
```

### After
```nushell
{name: Downloads} | format "{name}"
Downloads
```

# User-Facing Changes
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# Tests + Formatting
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crates/nu-cmd-extra/src/extra/strings/format/command.rs

@@ -1,3 +1,5 @@
+use std::vec;
+
 use nu_engine::{eval_expression, CallExt};
 use nu_parser::parse_expression;
 use nu_protocol::ast::{Call, PathMember};
@@ -17,15 +19,16 @@ impl Command for Format {
 
     fn signature(&self) -> Signature {
         Signature::build("format")
-            .input_output_types(vec![(
+            .input_output_types(vec![
-                Type::Table(vec![]),
+                (Type::Table(vec![]), Type::List(Box::new(Type::String))),
-                Type::List(Box::new(Type::String)),
+                (Type::Record(vec![]), Type::Any),
-            )])
+            ])
             .required(
                 "pattern",
                 SyntaxShape::String,
                 "the pattern to output. e.g.) \"{foo}: {bar}\"",
             )
+            .allow_variants_without_examples(true)
             .category(Category::Strings)
     }
 

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

@@ -16,6 +16,13 @@ fn creates_the_resulting_string_from_the_given_fields() {
     assert_eq!(actual.out, "nu has license ISC");
 }
 
+#[test]
+fn format_input_record_output_string() {
+    let actual = nu!(r#"{name: Downloads} | format "{name}""#);
+
+    assert_eq!(actual.out, "Downloads");
+}
+
 #[test]
 fn given_fields_can_be_column_paths() {
     let actual = nu!(

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

@@ -0,0 +1,12 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn test_char_list_outputs_table() {
+    let actual = nu!(pipeline(
+        r#"
+            char --list | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "107");
+}