Add types for knuth-shuffle (#41259)

* Add types for knuth-shuffle

This adds types for the [`knuth-shuffle`](https://www.npmjs.com/package/knuth-shuffle)  package.

* Correct return type to be same as passed array

This corrects the return type for the `knuthShuffle` function, as it returns an array of the same type (specifically, the same array!), rather than `void`.

* Correct tests

types/knuth-shuffle/index.d.ts

@@ -0,0 +1,6 @@
+// Type definitions for knuth-shuffle 1.0
+// Project: https://git.coolaj86.com/coolaj86/knuth-shuffle.js
+// Definitions by: Chris Atkin <https://github.com/atkinchris>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+export function knuthShuffle<T>(array: T[]): T[];

types/knuth-shuffle/knuth-shuffle-tests.ts

@@ -0,0 +1,4 @@
+import { knuthShuffle } from "knuth-shuffle";
+
+knuthShuffle([4, 8, 15, 16, 23, 42]); // $ExpectType number[]
+knuthShuffle(['a', 'b', 'c', 'd']); // $ExpectType string[]

types/knuth-shuffle/tsconfig.json

@@ -0,0 +1,23 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "knuth-shuffle-tests.ts"
+    ]
+}

types/knuth-shuffle/tslint.json

@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }