Add typings for npm module uid2 (#36207)

* Add typings for npm module uid2

* Add callback parameter to uid typing

* Refactor uid2 typings to different style

* Enable dt-header lint rule @types/uid2

* Fix tests

types/uid2/index.d.ts

@@ -0,0 +1,9 @@
+// Type definitions for uid2 0.0
+// Project: https://github.com/coreh/uid2
+// Definitions by: Levi Bostian <https://github.com/levibostian>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+declare function uid2(length: number): string;
+declare function uid2(length: number, callback: (err: Error | null, result?: string) => void): void;
+
+export = uid2;

types/uid2/tsconfig.json

@@ -0,0 +1,23 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "uid2-tests.ts"
+    ]
+}

types/uid2/tslint.json

@@ -0,0 +1,3 @@
+{
+    "extends": "dtslint/dt.json"
+}

types/uid2/uid2-tests.ts

@@ -0,0 +1,8 @@
+import uid2 = require('uid2');
+
+uid2(20); // $ExpectType string
+
+uid2(20, (error, result) => {
+    error; // $ExpectType Error | null
+    result; // $ExpectType string | undefined
+});