feat(rust): add create phone number kata

rust/tests/4_create_phone_number.rs

@@ -0,0 +1,20 @@
+fn create_phone_number(numbers: &[u8]) -> String {
+    let numbers = numbers.iter().map(|i| i.to_string()).collect::<String>();
+    format!("({}) {}-{}", &numbers[..3], &numbers[3..6], &numbers[6..])
+}
+
+#[test]
+fn returns_expected() {
+    assert_eq!(
+        create_phone_number(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]),
+        "(123) 456-7890"
+    );
+    assert_eq!(
+        create_phone_number(&[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]),
+        "(111) 111-1111"
+    );
+    assert_eq!(
+        create_phone_number(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 9]),
+        "(123) 456-7899"
+    );
+}