Add types for koa-requestid (#28676)

Simple interface for the koa-requestid Middleware.

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- [x ] Use a meaningful title for the pull request. Include the name of the package modified.
- [x ] Test the change in your own code. (Compile and run.)
- [x ] Add or edit tests to reflect the change. (Run with `npm test`.)
- [x ] Follow the advice from the [readme](https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/README.md#make-a-pull-request).
- [ x] Avoid [common mistakes](https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/README.md#common-mistakes).
- [x ] Run `npm run lint package-name` (or `tsc` if no `tslint.json` is present).

Select one of these and delete the others:

If adding a new definition:
- [x ] The package does not already provide its own types, or cannot have its `.d.ts` files generated via `--declaration`
- [x ] If this is for an NPM package, match the name. If not, do not conflict with the name of an NPM package.
- [ x] Create it with `dts-gen --dt`, not by basing it on an existing project.
- [x ] `tslint.json` should be present, and `tsconfig.json` should have `noImplicitAny`, `noImplicitThis`, `strictNullChecks`, and `strictFunctionTypes` set to `true`.

types/koa-requestid/index.d.ts

@@ -0,0 +1,15 @@
+// Type definitions for koa-requestid 2.0
+// Project: https://github.com/seegno/koa-requestid/
+// Definitions by: Steven McDowall <https://github.com/sjmcdowall>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.3
+
+import { Middleware } from 'koa';
+
+export = requestId;
+
+declare function requestId(options?: {
+    expose?: string;
+    header?: string;
+    query?: string;
+}): Middleware;

types/koa-requestid/koa-requestid-tests.ts

@@ -0,0 +1,10 @@
+import Koa = require('koa');
+import requestId = require('koa-requestid');
+const app = new Koa();
+
+app.use(requestId());
+app.use(async ctx => {
+    ctx.body = ctx.state.id;
+});
+
+app.listen(3000);

types/koa-requestid/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",
+        "koa-requestid-tests.ts"
+    ]
+}

types/koa-requestid/tslint.json

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