fix: empty tables now respect $env.config.use_ansi_coloring (closes #14896) (#15751)

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- fixes #14896
- related to #15163

# Description
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This PR fixes the presence of ansi color codes in empty tables, when
`$env.config.table.show_empty = true` and `$env.config.use_ansi_coloring
= false`

# User-Facing Changes
Empty tables respect `$env.config.use_ansi_coloring`

# Tests + Formatting
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Added a test for this case.

# After Submitting

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

@@ -3847,6 +3847,30 @@ fn table_colors() {
     assert_eq!(actual.out, "╭───┬───╮│ a │ 1 ││ b │ 2 │╰───┴───╯");
 }
 
+#[test]
+fn table_empty_colors() {
+    let actual = nu!("$env.config.use_ansi_coloring = true; []");
+    assert_eq!(
+        actual.out,
+        "\u{1b}[37m╭────────────╮\u{1b}[0m\u{1b}[37m│\u{1b}[0m \u{1b}[2mempty list\u{1b}[0m \u{1b}[37m│\u{1b}[0m\u{1b}[37m╰────────────╯\u{1b}[0m"
+    );
+
+    let actual = nu!("$env.config.use_ansi_coloring = true; {}");
+    assert_eq!(
+        actual.out,
+        "\u{1b}[37m╭──────────────╮\u{1b}[0m\u{1b}[37m│\u{1b}[0m \u{1b}[2mempty record\u{1b}[0m \u{1b}[37m│\u{1b}[0m\u{1b}[37m╰──────────────╯\u{1b}[0m"
+    );
+
+    let actual = nu!("$env.config.use_ansi_coloring = false; []");
+    assert_eq!(actual.out, "╭────────────╮│ empty list │╰────────────╯");
+
+    let actual = nu!("$env.config.use_ansi_coloring = false; {}");
+    assert_eq!(
+        actual.out,
+        "╭──────────────╮│ empty record │╰──────────────╯",
+    );
+}
+
 #[test]
 fn table_index() {
     let actual = nu!(