Specify minimal interface for websocketEndpoints, obviate @types/ws dependency

Summary:
Define the minimal interface we need for `runServer`'s `websocketEndpoints` option - the expectations is a `Websocket` implementation will be supplied, but since there are several of those for Node JS (`ws`, `websocket`) that broadly aim to implement the same web specification, I think it's best to be unopinionated in the type we require and just specify the parts of the interface Metro needs - this has been stable for some time.

The starting point for this type is from `types/ws`, here:
https://github.com/DefinitelyTyped/DefinitelyTyped/blob/a785fc80eb9e588cdef1e4c008225e167a8d925f/types/ws/index.d.ts#L349-L354

I've mirrored this change in Flow to ensure that our source is checked against the same rules we're exposing in TS.

Changelog:
```
* **[Types]** Remove dependency on `types/ws`
```

Reviewed By: huntie

Differential Revision: D44930635

fbshipit-source-id: b5b27fe4875aa39bf74d82b62463a9bd7c3846b9

Author: robhogan

packages/metro/package.json

@@ -63,7 +63,6 @@
   },
   "devDependencies": {
     "@babel/plugin-transform-flow-strip-types": "^7.0.0",
-    "@types/ws": "^8.5.4",
     "babel-jest": "^29.2.1",
     "dedent": "^0.7.0",
     "jest-snapshot": "^26.5.2",

packages/metro/src/index.flow.js

@@ -15,7 +15,8 @@ import type {CustomResolverOptions} from 'metro-resolver';
 import type {ReadOnlyGraph} from './DeltaBundler';
 import type {ServerOptions} from './Server';
 import type {OutputOptions, RequestOptions} from './shared/types.flow.js';
-import type {Server as HttpServer} from 'http';
+import type EventEmitter from 'events';
+import type {IncomingMessage, Server as HttpServer} from 'http';
 import type {Server as HttpsServer} from 'https';
 import type {
   ConfigT,
@@ -24,6 +25,7 @@ import type {
   Middleware,
 } from 'metro-config/src/configTypes.flow';
 import type {CustomTransformOptions} from 'metro-transform-worker';
+import type {Duplex} from 'stream';
 import typeof Yargs from 'yargs';
 
 const makeBuildCommand = require('./commands/build');
@@ -48,7 +50,6 @@ const {Terminal} = require('metro-core');
 const {InspectorProxy} = require('metro-inspector-proxy');
 const net = require('net');
 const {parse} = require('url');
-const ws = require('ws');
 
 type MetroMiddleWare = {
   attachHmrServer: (httpServer: HttpServer | HttpsServer) => void,
@@ -62,6 +63,15 @@ export type RunMetroOptions = {
   waitForBundler?: boolean,
 };
 
+interface WebsocketServer extends EventEmitter {
+  handleUpgrade<T = WebsocketServer>(
+    request: IncomingMessage,
+    socket: Duplex,
+    upgradeHead: Buffer,
+    callback: (client: T, request: IncomingMessage) => void,
+  ): void;
+}
+
 export type RunServerOptions = $ReadOnly<{
   hasReducedPerformance?: boolean,
   host?: string,
@@ -75,7 +85,7 @@ export type RunServerOptions = $ReadOnly<{
   waitForBundler?: boolean,
   watch?: boolean,
   websocketEndpoints?: $ReadOnly<{
-    [path: string]: typeof ws.Server,
+    [path: string]: WebsocketServer,
   }>,
 }>;
 

packages/metro/types/index.d.ts

@@ -14,7 +14,8 @@ export * from './ModuleGraph/worker/collectDependencies';
 export * from './Server';
 export * from './lib/reporting';
 
-import type {Server as HttpServer} from 'http';
+import type {EventEmitter} from 'events';
+import type {IncomingMessage, Server as HttpServer} from 'http';
 import type {Server as HttpsServer} from 'https';
 import type {
   ConfigT,
@@ -24,7 +25,7 @@ import type {
 } from 'metro-config';
 import type {CustomTransformOptions} from 'metro-babel-transformer';
 import type {ReadOnlyGraph} from './DeltaBundler/types';
-import type {Server} from 'ws';
+import type {Duplex} from 'stream';
 import Yargs = require('yargs');
 import type {default as MetroServer, ServerOptions} from './Server';
 import type {OutputOptions, RequestOptions} from './shared/types';
@@ -45,6 +46,15 @@ export interface RunMetroOptions extends ServerOptions {
   waitForBundler?: boolean;
 }
 
+interface WebsocketServer extends EventEmitter {
+  handleUpgrade<T = WebsocketServer>(
+    request: IncomingMessage,
+    socket: Duplex,
+    upgradeHead: Buffer,
+    callback: (client: T, request: IncomingMessage) => void,
+  ): void;
+}
+
 export interface RunServerOptions {
   hasReducedPerformance?: boolean;
   host?: string;
@@ -65,7 +75,7 @@ export interface RunServerOptions {
   waitForBundler?: boolean;
   watch?: boolean;
   websocketEndpoints?: {
-    [path: string]: Server;
+    [path: string]: WebsocketServer;
   };
 }
 

yarn.lock

@@ -1296,13 +1296,6 @@
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-2.0.0.tgz#7036640b4e21cc2f259ae826ce843d277dad8cff"
   integrity sha512-RJJrrySY7A8havqpGObOB4W92QXKJo63/jFLLgpvOtsGUqbQZ9Sbgl35KMm1DjC6j7AvmmU2bIno+3IyEaemaw==
 
-"@types/ws@^8.5.4":
-  version "8.5.4"
-  resolved "https://registry.yarnpkg.com/@types/ws/-/ws-8.5.4.tgz#bb10e36116d6e570dd943735f86c933c1587b8a5"
-  integrity sha512-zdQDHKUgcX/zBc4GrwsE/7dVdAD8JR4EuiAXiiUhhfyIJXXb2+PrGshFyeXWQPMmmZ2XxgaqclgpIC7eTXc1mg==
-  dependencies:
-    "@types/node" "*"
-
 "@types/yargs-parser@*":
   version "15.0.0"
   resolved "https://registry.yarnpkg.com/@types/yargs-parser/-/yargs-parser-15.0.0.tgz#cb3f9f741869e20cce330ffbeb9271590483882d"