[ramda] Add type for string-based reverse (#23927)

* Add type for string-based reverse

* Add test for string-based reverse

* Use separate documentation for each overload

types/ramda/index.d.ts

@@ -1601,6 +1601,10 @@ declare namespace R {
          * Returns a new list with the same elements as the original list, just in the reverse order.
          */
         reverse<T>(list: ReadonlyArray<T>): T[];
+        /**
+         * Returns a new string with the characters in reverse order.
+         */
+        reverse(str: string): string;
 
         /**
          * Scan is similar to reduce, but returns a list of successively reduced values from the left.

types/ramda/ramda-tests.ts

@@ -977,6 +977,13 @@ type Pair = KeyValuePair<string, number>;
     R.reverse([]);         // => []
 };
 
+() => {
+    R.reverse('abc');      // => 'cba'
+    R.reverse('ab');       // => 'ba'
+    R.reverse('a');        // => 'a'
+    R.reverse('');         // => ''
+};
+
 () => {
     const numbers = [1, 2, 3, 4];
     R.scan(R.multiply, 1, numbers); // => [1, 1, 2, 6, 24]