feat: fetch gateway information without requiring rest in ws (#10651)

* feat: overridable initial gateway URL

* chore: discussion changes

* chore: requested change

* chore: other changes

* Update packages/ws/src/ws/WebSocketManager.ts

* style: run ESLint

---------

Co-authored-by: Jiralite <33201955+Jiralite@users.noreply.github.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/ws/__tests__/strategy/WorkerShardingStrategy.test.ts

@@ -1,12 +1,8 @@
 /* eslint-disable id-length */
 import { setImmediate } from 'node:timers';
 import { REST } from '@discordjs/rest';
-import {
-	GatewayDispatchEvents,
-	GatewayOpcodes,
-	type GatewayDispatchPayload,
-	type GatewaySendPayload,
-} from 'discord-api-types/v10';
+import type { RESTGetAPIGatewayBotResult, GatewayDispatchPayload, GatewaySendPayload } from 'discord-api-types/v10';
+import { GatewayDispatchEvents, GatewayOpcodes, Routes } from 'discord-api-types/v10';
 import { MockAgent, type Interceptable } from 'undici';
 import { beforeEach, test, vi, expect, afterEach } from 'vitest';
 import {
@@ -159,7 +155,9 @@ test('spawn, connect, send a message, session info, and destroy', async () => {
 	const manager = new WebSocketManager({
 		token: 'A-Very-Fake-Token',
 		intents: 0,
-		rest,
+		async fetchGatewayInformation() {
+			return rest.get(Routes.gatewayBot()) as Promise<RESTGetAPIGatewayBotResult>;
+		},
 		shardIds: [0, 1],
 		retrieveSessionInfo: mockRetrieveSessionInfo,
 		updateSessionInfo: mockUpdateSessionInfo,