Use index.d.ts only (not foo/foo.d.ts) (#12834)

* Use index.d.ts only (not foo/foo.d.ts)

* Convert more packages

* Remove unnecessary references

webpack-dev-server/tsconfig.json

@@ -13,7 +13,7 @@
         "forceConsistentCasingInFileNames": true
     },
     "files": [
-        "webpack-dev-server.d.ts",
+        "index.d.ts",
         "webpack-dev-server-tests.ts"
     ]
 }

webpack-dev-server/webpack-dev-server-tests.ts

@@ -1,5 +1,3 @@
-/// <reference path="webpack-dev-server.d.ts" />
-
 import * as webpack from 'webpack';
 import * as WebpackDevServer from 'webpack-dev-server';
 var compiler = webpack({});
@@ -20,7 +18,7 @@ server = new WebpackDevServer(compiler, {
     // Enable special support for Hot Module Replacement
     // Page is no longer updated, but a "webpackHotUpdate" message is send to the content
     // Use "webpack/hot/dev-server" as additional module in your entry point
-    // Note: this does _not_ add the `HotModuleReplacementPlugin` like the CLI option does. 
+    // Note: this does _not_ add the `HotModuleReplacementPlugin` like the CLI option does.
 
     // Set this as true if you want to access dev server from arbitrary url.
     // This is handy if you are using a html5 router.