[natural-sort] Make definitions and tests match module (#25670)

The module is a function that takes options and returns a sort function.
It is not the sort function itself. The sort function also works on any
mixture of numbers and strings, as the module's own usage examples show.

The tests are just the usage examples verbatim.

types/natural-sort/index.d.ts

@@ -1,9 +1,18 @@
 // Type definitions for NaturalSort
 // Project: https://github.com/studio-b12/natural-sort
 // Definitions by: Antonio Morales <https://github.com/a-morales>
+//                 Brian Crowell <https://github.com/fluggo>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 export as namespace naturalSort;
 
-declare function naturalSort<T>(a: T, b: T): number;
+interface Options {
+    /** Set to true to make the sort case-sensitive. */
+    caseSensitive?: boolean;
+
+    /** Set to 'desc' to sort in reverse. */
+    direction?: 'desc'
+}
+
+declare function naturalSort(options?: Options): (a: string | number, b: string | number) => number;
 export = naturalSort;

types/natural-sort/natural-sort-tests.ts

@@ -1,5 +1,8 @@
 
 import naturalSort = require("natural-sort");
 
-[5, 3, 2, 4, 1].sort(naturalSort);
-["a", "c", "b", "z", "w", "l"].sort(naturalSort);
+['10. tenth', 'odd', 1, '', '2. second'].sort(naturalSort());
+[3, 4, 1, 5, 2].sort(naturalSort({direction: 'desc'}));
+
+['a', 'B'].sort(naturalSort());
+['a', 'B'].sort(naturalSort({caseSensitive: true}));